Devices for making reaction products by controlling transient conversion in an atomized liquid

ABSTRACT

Devices for making reaction products by atomizing into droplets a first liquid containing a first reactant into a gas containing a second reactant in a manner to form a reaction product within the droplets. The reaction is controlled by monitoring the transient conversion (conversion taking place in the time interval between the formation of the droplets and their coalescence into a mass of liquid) of first reactant to reaction product just before the droplets coalesce into a mass of a second liquid.

FIELD OF THE INVENTION

This invention relates to devices for making reaction products, whereina first reactant incorporated in an atomized liquid reacts with a gascontaining a second reactant, under controlled conditions.

BACKGROUND OF THE INVENTION

Reactions where a first reactant, dissolved in a liquid, reacts with asecond reactant contained in a gas under increased surface areaconditions are known to the art. Such reactions are carried out indevices as scrubbers, burners, reaction vessels, and the like, forexample.

Atomization of liquids into a gaseous atmosphere is one of the abovementioned techniques described in the art. The atomization techniquesfor conducting reactions, disclosed in the art so far, are rather crudeand lack innovative features for controlling such reactions with respectto: desired reaction product if the reaction product is an intermediate,yield in reaction product, conversion and conversion rate, temperatureprofiles in the reaction zone, average droplet size or diameter,evaporation rates, and the like. Actually in most, if not all, cases,the reaction product is substantially the final product expected underthe crude overall conditions of the reaction. For example, in the caseof a burner, where a fuel is atomized into an atmosphere of anoxygen-containing gas (such as air for example), the final product ofreaction is carbon dioxide, with desired minimization of carbon monoxideand nitrogen oxides as much as possible. In another example, a scrubberfor removing acidic compounds from a gas may use an atomized liquidcontaining alkali or alkaline earth compounds which react with theacidic compounds in the gas to form the corresponding salts. In stillanother example, ammonia and phosphoric acid react under atomizationconditions to form ammonium orthophosphate, which is a final reactionproduct.

On the other hand, reactions which are geared to produce intermediateproducts, especially in the case of oxidations, are not run underatomization conditions, since atomization promotes complete reactions toa final product. For example, oxidation of cyclohexane to adipic acid,or oxidation of p-xylene to terephthalic acid, have not been reported tobe conducted under atomization conditions, and there is no incentive inthe art to do so, since burning of cyclohexane to carbon dioxide hasbeen expected to take place under such conditions. However, theinventors have discovered that in the presence of unexpected intricatecritical controls and requirements of the instant invention,intermediate reaction or oxidation products, such as adipic acid,phthalic acid, isophthalic acid and terephthalic acid, for example, maybe advantageously obtained under atomization conditions.

The following references, among others, describe processes conducted inintermixing liquid with gaseous materials, mostly under increasedsurface area conditions.

U.S. Pat. No. 5,399,750 (Brunet al.) discloses methods for preparingmaleamic acid (aminomaleic acid) by reacting gaseous ammonia with moltenmaleic anhydride under reactant contact conditions of high surface area,for example reacting said gaseous NH₃ with a thin film of said moltenmaleic anhydride or with said molten maleic anhydride in a state ofvigorous agitation.

U.S. Pat. No. 5,396,850 (Conochie et al.) discloses a method ofdestroying organic waste in a bath of molten metal and slag contained ina vessel. The method comprises injecting organic waste into the bath toform a primary reaction zone in which the organic waste is thermallycracked and the products of the thermal cracking which are not absorbedinto the bath are released into the space above the surface of the bath.The method further comprises injecting an oxygen-containing gas towardthe surface of the bath to form a secondary reaction zone in the spaceabove the surface of the bath in which the oxidizable materials in theproducts from the primary reaction zone are completely oxidized and theheat released by such oxidation is transferred to the bath. In order tofacilitate efficient heat transfer from the second reaction zone to thebath, the method further comprises injecting an inert or other suitablegas into the bath to cause molten metal and slag to be ejected upwardlyfrom the bath into the secondary reaction zone.

U.S. Pat. No. 5,312,567 (Kozma et al.) discloses a complex mixing systemwith stages consisting of propeller mixers of high diameter ratio, wherethe blades are provided with flow modifying elements, whereby the energyproportions spent on dispersion of the amount of gas injected into thereactor, homogenization of the multi-phase mixtures, suspension of solidparticles, etc. and the properties corresponding to the rheologicalproperties of the gas-liquid mixtures and to the special requirements ofthe processes can be ensured even in extreme cases. Open channelsopposite to the direction of rotation are on the blades of thedispersing stage of the propeller mixers fixed to a common shaft, wherethe channels are interconnected with gas inlet. The angle of incidenceof a certain part of the blades of mixing stages used for homogenizationand suspension is of opposite direction and the length is shorter and/orthe angle of incidence is smaller than those of the other blades. Bafflebars are on the trailing end of the blades on a certain part of thepropeller mixers used similarly for homogenization and suspension,and/or auxiliary blades at an angle of max. 20° to the blade wings arearranged above or below the trailing end of the blades.

U.S. Pat. No. 5,244,603 (Davis) discloses a gas-liquid mixing systemwhich employs an impeller/draft tube assembly submerged in liquid.Hollow eductor tubes affixed to the impeller drive shaft are used toflow gas from an overhead gas space to the liquid in the vicinity of theassembly. The positioning and size of the eductor tubes are such as tomaximize the desired gas-liquid mixing and reaction rate.

U.S. Pat. No. 5,270,019 (Melton et al.) discloses an elongated,generally vertically extending concurrent reactor vessel for theproduction of hypochlorous acid by the mixing and reaction of a liquidalkali metal hydroxide and a gaseous halogen, wherein an atomizer ismounted near the top of the reactor vessel to atomize the liquid alkalimetal hydroxide into droplets in the vessel. The vessel has a sprayingand reaction zone immediately beneath the atomizer and a drying zonebeneath the spraying and reaction zone to produce a gaseous hypochlorousacid and a substantially dry solid salt by-product.

U.S. Pat. No. 5,170,727 (Nielsen) discloses a processes and apparatus inwhich supercritical fluids are used as viscosity reduction diluents forliquid fuels or waste materials which are then spray atomized into acombustion chamber. The addition of supercritical fluid to the liquidfuel and/or waste material allows viscous petroleum fractions and otherliquids such as viscous waste materials that are too viscous to beatomized (or to be atomized well) to now be atomized by this inventionby achieving viscosity reduction and allowing the fuel to produce acombustible spray and improved combustion efficiency. Moreover, thepresent invention also allows liquid fuels that have suitableviscosities to be better utilized as a fuel by achieving furtherviscosity reduction that improves atomization still further by reducingdroplet size which enhances evaporation of the fuel from the droplets.

U.S. Pat. No. 5,123,936 (Stone et al.) discloses a process and apparatusfor removing fine particulate matter and vapors from a process exhaustair stream, and particularly those emitted during post-production curingor post-treatment of foamed plastics, such as polyurethane foam, inwhich the exhaust air stream is passed through a transfer duct intowhich is introduced a water spray in the form of a mist of fine dropletsin an amount which exceeds the saturation point; thereafter the exhaustair stream is introduced into a filter chamber having a cross-sectionalarea that is substantially greater than that of the transfer duct, andthe exhaust air stream passes through at least one, and preferably aplurality of high surface area filters, whereby a portion of the wateris removed from the exhaust air stream and collected in the filterchamber prior to the discharge of the exhaust air stream into theenvironment.

U.S. Pat. No. 5,061,453 (Krippl et al.) discloses an apparatus forcontinuously charging a liquid reactant with a gas. The gas is dispersedin the reactant through a hollow stirrer in a gassing tank. The quantityof gas introduced per unit time is kept constant.

U.S. Pat. No. 4,423,018 (Lester, Jr. et al.) discloses a processaccording to which a by-product stream from the production of adipicacid from cyclohexane, containing glutaric acid, succinic acid andadipic acid, is employed as a buffer in lime or limestone flue gasscrubbing for the removal of sulfur dioxide from combustion gases.

U.S. Pat. No. 4,370,304 (Hendriks et al.) discloses methods by whichammonium orthophosphate products are prepared by reacting ammonia andphosphoric acid together at high speed under vigorous mixing conditionsby spraying the reactants through a two-phase, dual coaxial mixedsprayer and separately controlling the supply and axial outflow rate ofthe phosphoric acid at 1 to 10 m/sec. and the outflow rate of ammonia at200 to 1000 m/sec. (N.T.P.). Thorough mixing and a homogenous product isobtained by directing the outflow spray into a coaxial cylindricalreaction chamber of a specified size with respect to the diameter of theoutermost duct of the sprayer/mixer. The product may be granulated on amoving bed of granules and adjusted in respect of the NH₃ to H₃ PO₄content by changing the concentration of the phosphoric acid and/orsupplying additional ammonia to the granulation bed.

U.S. Pat. No. 4,361,965 (Goumondy et al.) discloses a device foratomizing a reaction mixture, said device enabling the reaction mixtureto be atomized in a reactor with the aid of at least a first gas and anatomizing nozzle. This device further comprises a supply of a second hotgas at the top of the atomizing device, serving to dry the atomizedmixture, a supply of a third gas and means for distributing this thirdgas comprising an annular space of adjustable width and adapted todistribute in the reactor said third gas in the form of a ring along theinner wall of the reactor, so as to avoid any contact between thereaction mixture and said wall. The invention is applicable to theatomization of a reaction mixture.

U.S. Pat. No. 4,308,037 (Meissner et al.) discloses methods according towhich high temperature thermal exchange between molten liquid and a gasstream is effected by generating in a confined flow passageway aplurality of droplets of molten liquid and by passing a stream throughthe passageway in heat exchange relationship with the droplets. Thedroplets are recovered and adjusted to a predetermined temperature bymeans of thermal exchange with an external source for recycle. Theprocess provides for removal of undesired solid, liquid or gaseouscomponents.

U.S. Pat. No. 4,065,527 (Graber) discloses an apparatus and a method forhandling a gas and a liquid in a manner to cause a specific interactionbetween them. The gas is placed into circulation to cause it to make aliquid circulate in a vortex fashion to present a liquid curtain. Thegas is then passed through the liquid curtain by angled vanes to causethe interaction between the two fluids, such as the heating of theliquid, scrubbing of the gas, adding a chemical to the liquid and thelike. The vanes are spaced apart and project inwardly from the innerperiphery of an annular support so that the circulating liquid readilymoves into the spaces between the vanes to create the liquid curtain. Anumber of embodiments of the invention are disclosed.

U.S. Pat. No. 4,039,304 (Bechthold et al.) discloses methods accordingto which waste gas is contacted with a solution of a salt from apollutant of the gas. This solution is obtained from another stage ofthe process used for cleaning or purifying the gas. The resultingmixture of gas and solution is subjected to vaporization so as to obtaina dry gaseous substance constituted by the waste gas and the evaporatedsolvent for the salt. The gaseous substance thus formed containscrystals of the salt as well as the pollutant present in the originalwaste gas. The salt crystals and other solid particles are removed fromthe gaseous substance in the form of a dry solids mixture. The gaseoussubstance is subsequently mixed with an absorption fluid such as anammonia solution in order to wash out and redissolve any salt crystalswhich may remain in the gaseous substance and in order to remove thepollutant present in the original waste gas from the gaseous substance.The pollutant and the redissolved salt crystals form a salt solutiontogether with the absorption fluid and it is this salt solution which isbrought into contact with the waste gas. The gaseous substance isexhausted to the atmosphere after being mixed with the absorption fluid.

U.S. Pat. No. 3,928,005 (Laslo) discloses a method and apparatus fortreating gaseous pollutants such as sulfur dioxide in a gas stream whichincludes a wet scrubber wherein a compressed gas is used to atomize thescrubbing liquid and a nozzle and the compressed gas direct the atomizedliquid countercurrent to the flow of gas to be cleaned. The method andapparatus includes pneumatically conveying to the nozzle a material suchas a solid particulate material which reacts with or modifies thepollutant to be removed or altered. The gas used for atomizing thescrubbing liquid is also used as a transport vehicle for the solidparticulate material. In the case of sulfur oxides, the material may bepulverized limestone.

U.S. Pat. No. 3,677,696 (Helsinki et al) discloses a method according towhich, the concentration of circulating sulfuric acid is adjusted to80-98% by weight and used to wash hot gases containing mercury. Thetemperature of the acid is maintained between 70°-250° C., and the solidmaterial separating from the circulating wash solution is recovered.

U.S. Pat. No. 3,613,333 (Gardenier) discloses a process and apparatusfor removing contaminants from and pumping a gas stream comprisingindirectly heat exchanging the gas and a liquid, introducing the liquidunder conditions of elevated temperature and pressure in vaporized andatomized form into the gas, mixing same thereby entrapping thecontaminants, and separating clean gas from the atomized liquidcontaining the contaminants.

U.S. Pat. No. 2,980,523 (Dille et al.) discloses a process for theproduction of carbon monoxide and hydrogen from carbonaceous fuels byreaction with oxygen. In one of its more specific aspects it is directedto a method of separating carbonaceous solid entrained in the gaseousproducts of reaction of carbonaceous fuels and oxygen wherein saidproducts are contacted with a limited amount of liquid hydrocarbon andthereafter scrubbed with water, and said carbonaceous solid is decantedfrom said clarified water.

U.S. Pat. No. 2,301,240 (Leuna et al.) discloses an improved process forremoving impurities from acetylene gas which has been prepared bythermal or electrical methods by washing with organic liquids, as forexample oils or tars.

U.S. Pat. No. 2,014,044 (Haswell) discloses an improved method fortreating gas and aims to provide for the conservation of the sensibleheat of such gas.

U.S. Pat. No. 1,121,532 (Newberry) discloses a processes of recoveringalkalis from flue-gases.

Currently, oxidation reactions for the production of organic acids,including but not limited to adipic acid, are conducted in a liquidphase reactor with reactant gas sparging. The reactant gas in thesecases is typically air, but may also be oxygen. Sufficient reactant gas,with or without non-reactive diluents (e.g., nitrogen), is sparged--atrelatively high rate--so that the liquid reaction medium is aerated tomaximum capacity (typically 15-25% aeration). The relatively highsparging rates of reactant containing gas feed (hereinafter referred toas "reactant gas"), associated with this conventional approach, haveseveral drawbacks:

Costly reactant gas feed compressors are required to compress makeupreactant gas for sparging. These are expensive to install and operate(high electric or steam consumption), and have many utility problemsresulting in excessive plant downtime.

The required high gas rate makes it extremely difficult to controloxygen content in the reactor at low concentrations (due to the highreactor gas turnover rate).

The required high gas rate makes it extremely difficult to controlreaction temperature at low production rates (i.e., high turndown rate)for a given sized reactor system. This occurs because the gas used forsparging removes energy from the reaction system by volatilizingreaction liquid and liquid solvent--this volatilization effect is quitesignificant at the relatively high temperatures commonly associated withand required for oxidation reactions. Unless carefully balanced by anexothermic heat of reaction, this volatilization will act tosubstantially lower the temperature of the liquid content of thereactor. Thus, a properly sparged system can be designed for goodtemperature control at medium to high production rates, but will suffertemperature loss and loss of temperature control at significant turndownrate.

High reactant gas feed rate results in relatively high reactornon-condensible off-gas rate. Non-condensible off-gases must either betotally purged to atmosphere, or--if oxygen content is high-partiallypurged and partially recycled to the reactor. The use of air as areactant gas feed has drawbacks because it results in high rate of purgeto the atmosphere--this is undesirable because this purge must first becleaned in very expensive off-gas cleanup facilities in order to meetever more stringent environmental requirements. The use of oxygen-onlygas feed to the reactor may be undesirable because high spargingrequirements result in low oxygen conversion in the reactor; lowconversion results in high oxygen concentration within the reactor; andhigh oxygen concentration within the reactor may result in excessiveover-oxidation of liquid reactants and liquid solvents with attendanthigh chemical yield loss (i.e., burning these to carbon monoxide andcarbon dioxide). If the oxygen in the reactor is diluted with recyclenitrogen or gaseous-recycle inerts, then both high recompressioninvestment and costs, and recompression utility problems are introduced.

The current technology also suffers from a relatively low ratio ofgas-liquid surface area to liquid reaction mass. The presently availableart does not maximize this ratio. In contrast, the present inventionmaximizes said ratio in order:

to increase reaction rate by increasing the mass transfer rate ofgaseous reactants to liquid reaction sites; and

so as to enable economic operation at relatively low concentration of asecond reactant, such as an oxidant for example, in the gas phase.

Operating at lower oxygen concentration with acceptable conversion ratesin the reactor improves yield by reducing over-oxidations, andeliminates safety (explosion) problems associated with operation in theexplosive oxygen/fuel envelope. In the current technology, reducingoxygen content below traditional levels would result in a non-economicreduction in reaction rate. However, a significant increase in theaforementioned ratio--relative to current levels--would offset this ratereduction thereby enabling economic operation at reduced oxygenconcentration in the reactor.

Another problem with the current technology is the sometimes formationof large agglomerations of insoluble oxidation products in the reactor.These can build up on reactor walls resulting in decreased availablereaction volume, and in unwanted by-product formation due toover-exposure of said accretions to reaction conditions (e.g., hightemperature) in oxygen-starved micro-reactor environments. These canalso form large diameter, heavy solids in the reactor which can resultin damage to expensive reactor agitator shafts and agitator sealsresulting in costly repairs and high utility wear-problems. Finally, thecurrent technology often requires expensive agitation shafts and sealscapable of withstanding corrosive chemical attack and containing highsystem pressures.

Substituting gas-phase reaction systems for liquid-phase reactorsintroduces new problems, chief among which is the difficulty ofidentifying a cost-effective, efficient, non-plugging, long-livedcatalyst system. Liquid-phase catalyst systems are well-developed andwell-understood. Unfortunately, these are non-volatile. Using anon-volatile catalyst in a gas-phase reaction system must necessarilyoften be subject to severe plugging problems as most organic acidsresulting from oxidation reactions are non-volatile solids--unlessdissolved in a liquid reaction medium.

There is a plethora of references dealing with oxidation of organiccompounds to produce acids, such as, for example, adipic acid.

The following references, among the plethora of others, may beconsidered as representative of oxidation processes relative to thepreparation of diacids.

U.S. Pat. No. 5,321,157 (Kollar) discloses a process for the preparationof C₅ -C₈ aliphatic dibasic acids through oxidation of correspondingsaturated cycloaliphatic hydrocarbons by

(1) reacting, at a cycloaliphatic hydrocarbon conversion level ofbetween about 7% and about 30%,

(a) at least one saturated cycloaliphatic hydrocarbon having from 5 to 8ring carbon atoms in the liquid phase and

(b) an excess of oxygen gas or an oxygen containing gas mixture

in the presence of

(c) less than 1.5% moles of a solvent per mole of cycloaliphatichydrocarbon (a), wherein said solvent comprises an organic acidcontaining only primary and/or secondary hydrogen atoms and

(d) at least about 0.002 mole per 1000 grams of reaction mixture of apoly valent heavy metal catalyst; and

(2) isolating the C₅ -C₈ aliphatic dibasic acid.

U.S. Pat. No. 5,221,800 (Park et al.) discloses a process for themanufacture of adipic acid, according to which cyclohexane is oxidizedin an aliphatic monobasic acid solvent in the presence of a solublecobalt salt wherein water is continuously or intermittently added to thereaction system after the initiation of oxidation of cyclohexane asindicated by a suitable means of detection, and wherein the reaction isconducted at a temperature of about 50° C. to 150° C., at an oxygenpartial pressure of about 50 to about 420 pounds per square inchabsolute.

The following references, among others, describe oxidation processesconducted in multi-stage and multi-plate systems.

U.S. Pat. No. 3,987,100 (Barnette et al.) describes a process ofoxidizing cyclohexane to produce cyclohexanone and cyclohexanol, saidprocess comprising contacting a stream of liquid cyclohexane with oxygenin each of at least three successive oxidation stages by introducinginto each stage a mixture of gases comprising molecular oxygen and aninert gas.

U.S. Pat. No. 3,957,876 (Rapoport et al.) describes a process for thepreparation cyclohexyl hydroperoxide substantially free of otherperoxides by oxidation of cyclohexane containing a cyclohexane solublecobalt salt in a zoned oxidation process in which an oxygen containinggas is fed to each zone in the oxidation section in an amount in excessof that which will react under the conditions of that zone.

U.S. Pat. No. 3,530,185 (Pugi) describes a process for manufacturingprecursors of adipic acid by oxidation of an oxygen containing inert gaswhich process is conducted in at least three successive oxidation stagesby passing a stream of liquid cyclohexane maintained at a temperature inthe range of 140° to 200° C., and a pressure in the range of 50-350 psigthrough each successive oxidation stage in an amount such thatsubstantially all the oxygen introduced into each stage is consumed inthat stage thereafter causing the residual inert gases to passcountercurrent into the stream of liquid during the passage of thestream through said stages.

None of the above references, or any other references known to theinventors disclose, suggest or imply, singly or in combination, devicesfor conducting reactions under atomization conditions subject to theintricate and critical controls and requirements of the instantinvention as described and claimed.

SUMMARY OF THE INVENTION

As aforementioned, the present invention relates to devices for makingreaction products, wherein a first reactant incorporated in an atomizedliquid reacts with a gas containing a second reactant, under controlledconditions. More particularly, this invention pertains a device forpreparing a reaction product from a first liquid containing a firstreactant and a gas containing a second reactant comprising:

a reaction chamber having an upper end, a lower end, a wall, and

a reaction zone, in which zone the first liquid is brought in contactwith the gas for reacting at a reaction pressure;

an atomizer disposed within the reaction chamber adapted to break thefirst liquid into a plurality of droplets within the gas at anatomization temperature in a manner that the droplets coalesce on a massof a second liquid containing reaction product, the mass of the secondliquid having a second liquid surface, the atomizer being away from saidsecond liquid surface at an atomization distance;

a conversion detector for monitoring transient conversion of the firstreactant and the second reactant to reaction product in the dropletsbefore the droplets coalesce onto the mass of the second liquid;

a controller connected to the conversion detector for pointing saidtransient conversion in the droplets toward a predetermined conversionrange; and

a separator for separating the reaction product from the second liquid.

Transient conversion is the conversion taking place in the time intervalbetween the formation of the droplets and their coalescence into a massof liquid. For more details see more detailed explanations at the lastsection of this specification.

Atomization temperature is the temperature of the first liquid in theatomizer, just before the first liquid has been atomized.

The methods and devices of the instant invention give vastly superiorcontrol over conventional methods and devices, since any reactionstaking place within the droplets, substantially freeze (substantiallystop) as the droplets coalesce. This, combined with measurements ofmiscellaneous characteristics of the droplets, just before they coalesceinto the second liquid (where the reaction substantially freezes), giveskey information on how to change different reaction parameters in orderto control the reaction in an unprecedented mariner.

By the phrase "a controller for pointing said transient conversion inthe droplets toward a predetermined conversion range", it is meant thatthe controller is adapted to change one or more parameters, such as thepreferable parameters listed as an example below, so that said changewill favor a respective change in the transient conversion toward thepredetermined range.

Depending on the reaction characteristics, some parameters or variablesmay be more or less effective in causing changes to the transientconversion. It is possible in some occasions that changes in oneparameter may not be capable to bring the transient conversion withinthe predetermined range. In such cases, the controller is preferablyadapted or programmed to select and change one or more additionalvariables in order to receive the desired result.

In the description of the preferred embodiments of the instantinvention, it is assumed for purposes of clarity that the particularvariable under consideration is capable by itself to bring the transientconversion within the predetermined range. This is generally true,provided that for a particular reaction to be conducted in the devicesand by the methods of this invention, the most efficient variable(s) hasbeen selected to be controlled by the controller. It should beunderstood, however, that the selection of one or more additionalvariables is well within the scope of this invention.

It is preferable that the droplets have an average droplet diameter andare produced at a desired first flow rate, the gas flows at a secondflow rate, the droplets contain volatile ingredients volatilizing at avolatilization rate, the first liquid contains first reactant at a firstcontent, the gas contains second reactant at a second content, and thecontroller is adapted to point the transient conversion toward thepredetermined range by changing a variable selected from a groupconsisting of

changing the atomization temperature,

changing the reaction pressure,

changing the atomization distance,

changing the average droplet diameter,

changing the first flow rate,

changing the second flow rate,

changing the volatilization rate,

changing the first content,

changing the second content, and

a combination thereof.

It is preferable that the conversion detector comprises a chromatographyapparatus, and more preferable that it comprises a High PerformanceLiquid Chromatography apparatus, especially when the reaction product isan acid.

It is also preferable that the device is adaptable to handle suchreactions, in which a major portion of the reaction product is anorganic compound, such as an intermediate oxidation product differentthan CO, CO₂, or a mixture thereof, for example, and/or the secondreactant is oxygen. By the expression "major portion" referring to acertain compound or compound group, it is meant that the weight of thecompound or compound group is higher than the weight of any otherindividual by-product formed.

Examples of reaction products are organic acids, such as for exampleadipic acid, phthalic acid, isophthalic acid, terephthalic acid, among aplethora of other compounds.

The predetermined transient conversion range is preferably in the rangeof 5% to 80%, more preferably in the range of 10-70%, and even morepreferably in the range of 20-60%.

The first reactant, preferably comprises a compound selected from agroup consisting of cyclohexane; cyclohexanone, cyclohexanol,cyclohexylhydroxyperoxide, o-xylene; p-xylene; m-xylene, a mixture of atleast two of cyclohexane, cyclohexanone, cyclohexanol,cyclohexylhydroxyperoxide, and a mixture of at least two of o-xylene,p-xylene, and m-xylene.

It is also preferable that

the first reactant comprises a compound selected from a group consistingof cyclohexane, cyclohexanone, cyclohexylhydroxyperoxide, cyclohexanol,o-xylene, m-xylene, p-xylene, a mixture of at least two of cyclohexane,cyclohexanone, cyclohexanol, cyclohexylhydroxyperoxide, and a mixture ofat least two of o-xylene, p-xylene, and m-xylene.

the oxidant comprises oxygen; and a major portion of the reactionproduct comprises a compound selected from a group consisting of adipicacid, cyclohexanol, cyclohexanone, cyclohexylhydroperoxide, phthalicacid, isophthalic acid, terephthalic, a mixture of at least two ofadipic acid, cyclohexanone, cyclohexanol, and cyclohexylhydroxyperoxide,and a mixture of at least two of phthalic acid, isophthalic acid, andterephthalic acid.

It is also preferable that the atomizer is disposed toward the upperend, and directed toward the lower end at the atomization distance, andeven more preferable that the atomizer is airless.

The device may comprise a recirculation branch for recirculating atleast part of the second liquid, wherein the branch is preferablyfurnished with a recirculation tank for providing a third liquidcontaining first reactant to be added to the first liquid to replenishfirst reactant consumed during the reaction.

When the reaction product is a solid, the separator preferably comprisesa filtration apparatus for separating at least part of said reactionproduct from the second liquid.

An adequate amount of antistatic compound, preferably water, may beadded to a component selected from a group consisting of the firstliquid, the gas, and a combination thereof, in order to preventdevelopment of electrostatic charges and sparking.

The device may further comprise an internal condenser for condensingcondensibles at substantially reaction pressure, and/or means forproviding a thick film of liquid or curtain on the wall of the reactionchamber.

The device may further comprise a second reaction chamber and a secondatomizer inside said second reaction chamber adapted to atomize asolution comprising metal ions of a lower oxidation state in a manner toform a plurality of droplets in the second reaction chamber, the secondreaction chamber containing a gas comprising an oxidant adapted to causeat least partial oxidation of the metal ions to a higher valance state,the device further comprising means for feeding the solution containingthe oxidized metal ions to a desired section of the device.

Preferable catalyst for the oxidation of cyclohexane to adipic acid forexample comprises cobalt ions. The cobalt ions may be added to the firstliquid either as cobaltous, or preferably as cobaltic ions. The level ofcatalyst in the first liquid can be varied in order to control thetransient conversion. Higher amounts of ions, preferably cobaltic forfaster response, favor the increase of transient conversion, while loweramounts of ions favor the decrease of transient conversion.

BRIEF DESCRIPTION OF THE DRAWING

The reader's understanding of this invention will be enhanced byreference to the following detailed description taken in combinationwith the drawing figures, wherein:

FIG. 1 illustrates schematically a preferred embodiment of the presentinvention, wherein control of transient conversion is achieved bychanging the atomization distance through a movement of the atomizer.

FIG. 2 illustrates schematically another preferred embodiment of thepresent invention, wherein control of transient conversion is achievedby changing the atomization temperature.

FIG. 3 illustrates schematically still another preferred embodiment ofthe present invention, wherein control of transient conversion isachieved ether by changing the pressure in the reaction chamber, or bychanging the second flow rate, or by changing the second content.

FIG. 4 illustrates schematically still another preferred embodiment ofthe present invention, wherein control of transient conversion isachieved by changing the first content.

FIG. 5 illustrates schematically still another preferred embodiment ofthe present invention, wherein control of transient conversion isachieved by changing the droplet size or diameter.

FIG. 6 illustrates schematically still another preferred embodiment ofthe present invention, wherein control of transient conversion isachieved by changing the first flow rate.

FIG. 7 illustrates schematically still another preferred embodiment ofthe present invention, wherein control of transient conversion isachieved by changing the volatilization rate.

FIG. 8 illustrates schematically still another preferred embodiment ofthe present invention, wherein control of transient conversion isachieved by changing the atomization distance through moving the levelof the surface of the second liquid

FIG. 9 illustrates schematically the sample collector utilized in theembodiment of FIG. 8.

FIG. 10 illustrates schematically a filter arrangement comprised in theseparator according to another preferred embodiment of the presentinvention.

FIG. 11 illustrates schematically still another preferred embodiment ofthe present invention, wherein an eductor is utilized to recirculatenon-condensible off-gases, a condenser is used to condense condensibles,and part of the condensibles return to the reaction chamber, where athick film or curtain is formed for preventing solids buildup on thewalls.

FIG. 12 illustrates schematically still another preferred embodiment ofthe present invention, wherein a pump is utilized to recirculatenon-condensible off-gases, a condenser is used to condense condensibles,and part of the condensibles return to the reaction chamber, where athick film or curtain is formed for preventing solids buildup on thewalls.

FIG. 13 illustrates schematically still another preferred embodiment ofthe present invention, wherein both condensibles and non-condensiblesleave the reactor through the lower end.

FIG. 14 illustrates schematically still another preferred embodiment ofthe present invention, wherein a cooling mantle surrounds the reactionchamber.

FIG. 15 illustrates schematically still another preferred embodiment ofthe present invention, wherein a cooling coil performs condensationinside the reaction chamber.

FIG. 16 illustrates schematically still another preferred embodiment ofthe present invention, wherein condensation is performed by spraying acooling liquid along with atomization of the first liquid.

FIG. 17 illustrates schematically still another preferred embodiment ofthe present invention, wherein condensation is performed by sprayed acooling liquid towards the walls of the reaction chamber.

FIG. 18 illustrates schematically an apparatus for oxidizing metal ioncatalysts according to this invention.

DETAILED DESCRIPTION OF THE INVENTION

As aforementioned, the present invention relates to devices for makingreaction products, and preferably intermediate oxidation products,wherein a first reactant incorporated in an atomized liquid reacts witha gas containing a second reactant, which may preferably be an oxidant,under controlled conditions. The term "intermediate oxidation product",as aforementioned, signifies that the oxidation stops beforesubstantially oxidizing the first reactant to carbon monoxide, carbondioxide, or mixtures thereof. According to the present invention, theatomization conditions are subject to intricate critical controls andrequirements as described and claimed hereinbelow.

As also aforementioned, reactions which are geared to produceintermediate products, especially in the case of oxidations, have notrun under atomization conditions so far, since atomization promotescomplete reactions to a final product. For example, oxidation ofcyclohexane to adipic acid, or oxidation of p-xylene to terephthalicacid, have not been reported to be conducted under atomizationconditions, and there is no incentive in the art to do so, since burningof cyclohexane to carbon dioxide has been expected to take place undersuch conditions. However, the inventors have discovered that in thepresence of unexpected intricate critical controls and requirements ofthe instant invention, intermediate reaction or oxidation products, suchas adipic acid, phthalic acid, isophthalic acid and terephthalic acid,for example, may be advantageously obtained under atomizationconditions.

The present invention enables economic oxidation reactions at improvedyield with reduced compression costs and investment, using provencatalyst systems, with reduced off-gas waste-stream discharge to theatmosphere, with reduced off-gas cleanup investment and costs, withoutsolids plugging or buildup problems, with high utility, high conversionrates, and with reduced oxygen concentrations in the reaction chamber.

The ability to operate at lower oxygen concentration, made possible bythis invention, with acceptable conversion rates in the reactor improvesyield by reducing over-oxidations, and may eliminate safety (explosion)problems associated with operation in the explosive oxygen/fuel envelopeby operating in the non-explosive oxygen/fuel envelope. In the currenttechnology, reducing oxygen content below traditional levels wouldresult in a non-economic reduction in reaction rate. In this invention,however, a significant increase in the ratio of gas-liquid interfacialarea to liquid reaction mass--relative to current levels-offsets thisrate reduction, thereby enabling economic operation at reduced oxygenconcentration in the reactor.

Some of the key elements, which may be present singly or in anycombination thereof, in the embodiments of the present invention, are:

High productivity reaction volume;

Elimination of reactor agitator and agitator seals;

Efficient Catalyst Systems;

Low off-gas waste-stream rate;

Employment of an ultra-high ratio of gas/liquid interfacial area toliquid reaction volume;

Employment of an ultra-low ratio of liquid reaction volume to liquidvolume contained in the liquid-film diffusion zone attached to the gasinterface;

Variation and accurate control of the ratio of gas/liquid interfacialarea to liquid reaction volume, and the ratio of liquid reaction volumeto liquid volume contained in the liquid-film diffusion zone attached tothe gas interface;

Multi-parameter control of liquid reactant conversion;

Multi-parameter control of liquid reaction mass temperature;

Avoidance of solids buildup in the reactor;

Internal condensation; and

Easy recovery of high purity, high oxygen-concentration off-gas forrecycle with low recompression requirements.

This invention provides a more productive reaction volume than does theconventional technology. Reaction chamber productivity per unit liquidreaction volume is increased due to the greatly enhanced mass transferrates afforded by this invention, coupled, if so desired, with measuresto maximize droplet loading in the reaction chamber. Droplet loading inthe reaction chamber may be maximized according to the presentinvention, by employing internal condensation and generating ultra-smallliquid reaction droplets. The droplet loading, measured as a percent ofreaction chamber volume occupied by the totality of the droplets in thereaction chamber at any one time, is preferably maintained in the rangeof 1-40%. More preferably, droplet loading is maintained in the range of5-30%. More preferably still, droplet loading is maintained in the rangeof 10-20%. Excessively high droplet loading can lead to sudden anduncontrolled coalescence, and is to be avoided. Too low droplet loadingcan lead to low reaction chamber productivity. The optimal control ofdroplet loading and initial droplet size minimizes the coalescence ofdroplets, while in the reaction chamber, optimizes the mass transfer ofoxygen or other oxidant from the gas phase to the liquid phase, andmaximizes the liquid reaction volume available to support the desiredproduct formation.

As it will become clear in the course of this discussion, unlike in theconventional technology which utilizes sparging of oxidizing gasesthrough mechanically agitated liquids containing reactants to beoxidized, there is no reaction chamber agitator and no agitator seals.This process simplification is made possible by the unique reactionenvironment provided by this invention, and is highly desirable as itreduces cost, investment, and improves plant utility compared to theconventional technology.

Since according to the present invention the reaction is conductedwithin the droplets, which are in a liquid phase, the process stillmaintains the advantage of being able to employ efficient liquid-solublecatalyst systems, with the added advantage of attaining reactionconditions almost as efficient as those encountered in a homogeneousgaseous phase. Reactions in a gaseous phase would require costly anduncertain gas-phase catalysts or solid-phase catalyst systems.

Further, this invention enables a low off-gas waste-stream rate, if sodesired, which reduces the off-gas waste-stream rate to the environment,and reduces off-gas cleanup investment and costs. The low off-gaswaste-stream rate may be made possible with a near-stoichiometricgaseous oxygen feed combined with high conversion rates and/or chemicalyields, for example.

In the conventional technology, reaction chamber non-condensible off-gasis commonly purged to the atmosphere without partial recycle back to thereaction chamber. This results in increased oxygen consumption andrelated cost, but is done to avoid high, non-economic recompressioncosts and investment. In the conventional technology, recompressioncosts and investment are high due to a high non-condensible load, andhigh recycle pressure requirement:

high non-condensible load results from the relatively high chemicalyield loss, and--in most instances--the use of air as the oxygen source;

high recycle pressure is required to accommodate the high-pressure drop,subsurface sparging (into a liquid-filled reaction chamber) used in theconventional technology;

the high-pressure drop is required, in the case of subsurface sparging,to overcome the liquid head in the reaction chamber and to providehigh-power mixing; and

high-power mixing is necessary, in the case of the conventionaltechnology, to improve gas/liquid contacting and thereby accelerate therate of oxygen transfer into the liquid phase.

When condensation is employed at a stage before the pressure drop(internal condensation), as shown in the embodiment of FIG. 11 (beforevalve 864) for example, the increased oxygen consumption and relatedcost, and the high, non-economic recompression costs and investmentassociated with the conventional technology are avoided. According tothis embodiment, it is possible to recycle oxygen-containing off-gasback to the reaction chamber with relatively low or no recompressionrequirement and cost. The recycle may be even eliminated withoutincurring significant adverse economic impact. When condensation isemployed at such a stage, the recompression requirement isminimal--compared to the conventional technology--due to the lownon-condensible off-gas rate, especially when near-stoichiometric oxygenfeed is used. The low non-condensible off-gas rate is due to thecombination of near-stoichiometric oxygen feed, with one or more of highconversion rate, high chemical yield, and internal condensation, enabledand provided for by the instant invention.

According to the instant invention, when near-stoichiometric oxygen feedis desired, it is achievable by the high conversion of the oxygen feedto the reaction chamber per pass, hence needing little recyclerequirement. The high chemical yield results in low non-condensibleby-product formation, thereby significantly reducing off-gas purge loadgenerated in the reaction chamber. Reduced off-gas purge load in turnreduces oxygen purge from the reaction chamber. Reduced oxygen purgefrom the reaction chamber minimizes oxygen recycle requirement. Theimplementation of internal condensation further reduces recompressionrequirement, as internal condensation outside the reactor furtherreduces oxygen recycle required, and the implementation of internalcondensation inside the reactor reduces oxygen recycle requirementfurther still. This internal condensation significantly reduces oxygenphysical yield-loss. In the limit, internal condensation, completeoxygen conversion per pass, i.e., stoichiometric oxygen feed, and zeronon-condensible by-product formation would result in zero oxygenphysical yield loss and zero recompression requirement. Due to the lownon-condensible off-gas rate made possible when internal condensation isemployed, it is significantly less costly (compared to the conventionaltechnology) to forego recycle.

In this invention, solids buildup in the reaction chamber is preventedby washing the walls of the reaction chamber with preferably cooler,preferably catalyst-free liquid solvent, or with preferablycatalyst-free liquid reactant, or with a mixture thereof. All surfacesof the reaction chamber, or a certain portion of those surfaces prone tosolids buildup, may be washed in this manner. The wash liquid may besprayed onto the surfaces so washed, or may be generated in situ as aresult of internal condensation. Solids buildup is prevented because thesolids in contact with these surfaces are continuously washed out of thereaction chamber. Furthermore, reaction in the wash-liquid is greatlyminimized by the lower temperature or absence of catalyst, the shorthold-up-time or a combination thereof. All solids produced in thereaction chamber are removed from the reaction chamber with the washliquid.

In the embodiments of this invention involving off-gas recycle, thisinvention provides means by which the recompression requirement can begreatly minimized or eliminated. Due to the small non-condensibleoff-gas rate associated with this invention, it is possible to educt therecycle off-gas into the reaction chamber using a liquid stream as themotive force.

In the conventional technology, gas sparging bubbles are dispersed in acontinuous liquid-phase comprised of liquid reactants, liquid solvents,dissolved reaction products and by-products, dissolved gases, anddissolved catalysts. A thin film of liquid is attached and surroundseach bubble, due to strong surface tension forces. While the thicknessof the liquid-film is a function of many variables including, but notlimited to, temperature and viscosity of the liquid solvent and liquidreactant, generally the thickness of the liquid-film is in the range of0.05 inches to 0.0001 inches, and mostly in the range of 0.02 inches to0.001 inches. Reactions can occur in this liquid-film and in thecontinuous-phase liquid surrounding this film. Reaction products may infact be preferentially produced in the film, relative to the surroundingliquid, depending on the nature of the diffusional resistance inhibitingthe transfer of materials from the liquid film into the surroundingliquid. In any event, it is expected that a significant amount ofreaction will occur in the liquid-film due to its immediate proximity tothe gas-phase second reactant, such as oxygen or other oxidant forexample. In the conventional technology, the ratio of liquid reactionvolume to liquid volume in the liquid-film is extremely high--typically,this would be several orders of magnitude. This extremely high ratioleads to two highly undesirable consequences:

First, it leads to gross non-homogeneities in the concentration ofreaction products between the two zones, with high localized productconcentrations building up in the liquid-film. These high localizedconcentrations arise in the liquid-film in the conventional technologybecause a significant (perhaps even predominant) amount of reactionoccurs in the liquid-film due to its immediate proximity to thegas-phase reactant, and because reaction products so formed in theliquid-film must necessarily increase in concentration--relative to thesurrounding bulk liquid--to overcome diffusional resistance and migratefrom the liquid-film out into the surrounding liquid. Furthermore, for agiven production rate and conversion, the higher the ratio the higherthe product concentration in the liquid-film. The worst consequence ofhigh localized product concentration in the liquid-film in theconventional technology is that it leads directly to over-reactionproducts, such as over-oxidation for example. Over-oxidation resultswhen already formed product continues to be exposed to reactive forms ofoxygen. Over-oxidation in turn causes chemical yield loss, high productpurification costs, and high waste disposal costs.

Second, it leads to poor utilization of the total available reactionvolume. This results because the most productive reaction volume is thatin closest proximity to the gas-phase oxygen. The reaction volumeclosest to the gas-phase oxygen is the liquid film. At very high ratiosthe amount of volume occupied by the liquid-film is extremely small;hence, the poor utilization at high reaction volume.

This invention overcomes the aforementioned problems associated with theconventional technology by converting the reaction system to ultra-lowratio of liquid reaction volume to liquid volume in the liquid-film.This is the exact opposite of the conventional technology. In thisinvention, ultra-low ratios are obtained by converting the bulk stirredliquid phase to spray droplets of controlled small size suspended in thecontinuous gas-phase. The size of the droplets may be controlled suchthat the average radius of the droplet is preferably less than about 10times the thickness of the diffusion film associated with theconventional technology. More preferably, the droplets should becontrolled such that the average radius of the droplet is on less thanabout 5 times the thickness of the diffusion film associated with theconventional technology. More preferably still, the droplets are to becontrolled such that the average radius of the droplet is less thanabout 1 time the thickness of the diffusion film associated with theconventional technology. In this way, the ratio can be decreased byorders of magnitude below that possible in the conventional technology.This is highly desirable because it enables a significant reduction inover-reaction with concomitant reduction in impurity levels, reductionin purification costs and investment, and reduction in waste-streamload, without loss of production rate, and with more efficientutilization of liquid reaction volume in the reaction chamber (comparedto the conventional technology).

Further, in the conventional technology, the ability to generate a highratio of gas/liquid interfacial area to liquid reaction volume isconstrained by natural effects (including liquid surface tension) tocertain practical maximums. Heroic efforts, including high gas spargingrates and powerful agitation systems, have been employed to achieveoperation near the upper maximum limit. The inventors theorized that amuch higher ratio would be desirable, since it would facilitate thediffusion of oxygen reactant into a liquid film surrounding each gasbubble. This film is strongly attached to the bubble by strong surfacetension forces. Reaction can occur in this film and in thecontinuous-phase liquid surrounding this film, and the ability to effectreaction in either zone is dependent on oxygen diffusion from thegas-phase into the film. In the conventional technology, higherdiffusion rates may be only achieved by either increasing oxygen orother oxidant concentration in the gas passing through the liquidreaction phase, or by increasing the gas sparging rate. However, this isof very limited value, and only small improvements in diffusion ratesmay be made.

In contrast, according to this invention, huge improvements in diffusionrates may be made by using ultra-high ratios of gas/liquid interfacialarea to liquid reaction volume, which are obtained by converting thebulk stirred liquid phase into spray droplets of controlled small sizewithin a continuous gas-phase. For this purpose also, the size of thedroplets should be controlled such that the radius of the droplet is onaverage preferably less than about 10 times the thickness of thediffusion film associated with the conventional technology. Morepreferably, the droplets should be controlled such that the radius ofthe droplet is on average less than about 5 times the thickness of thediffusion film associated with the conventional technology. Morepreferably still, the droplets are to be controlled such that the radiusof the droplet is on average less than 1 time the thickness of thediffusion film. By this method, the ratio of gas/liquid interfacial areato liquid reaction volume can be increased by orders of magnitude abovethat possible in the conventional technology. This is highly desirablebecause it enables a significant reduction in the oxygen concentrationin the gas-phase without loss of production rate (compared to theconventional technology), or, alternately, higher oxygen diffusion rates(hence higher production rates) at comparable oxygen concentration inthe gas-phase.

The significant reduction in the oxygen concentration in the gas-phase,concurrent with still maintaining desirable high reaction rates, madepossible by this invention, is extremely desirable because it acts toimprove yield by reducing over-oxidation, improve safety by enablingoperation further away from the oxygen/fuel explosive envelope, andminimize the amount of oxygen swept from the reaction chamber.Minimizing the amount of oxygen swept from the reaction chamber withother non-condensibles is desirable because it significantly reduces:(1) costly investment for waste off-gas environmental cleanupfacilities, (2) waste off-gas discharges to the environment, and (3)very expensive, high maintenance, and potentially unsafe recompressionrequirements (all three of which cause problems in the conventionaltechnology).

According to the present invention, variation and accurate control ofthe ratio of gas/liquid interfacial area to liquid reaction volume, andthe ratio of liquid reaction volume to liquid volume contained in theliquid-film at the gas interface are provided. Since, in the presentinvention, the gas-phase is the continuous-phase, both ratios may besimultaneously controlled by controlling the average droplet size andthe droplet size distribution spectrum. For small droplets, surfacetension forces will pull the droplets into near spheres. For sphericaldroplets, the ratio of gas/liquid interfacial area to liquid reactionvolume is inversely proportional to droplet diameter, and the ratio ofliquid reaction volume to liquid volume contained in the liquid-film isdirectly proportional to droplet diameter. Consequently, ultra-highratio of gas/liquid interfacial area to liquid reaction volume andultra-low ratio of liquid reaction volume to liquid volume contained inthe liquid-film can be simultaneously achieved and controlled byreducing droplet diameter to very small, controlled diameters.Specifically, as aforementioned, the size of the droplets is to becontrolled such that the diameter of the droplet is on average less than10 times the thickness of the liquid-film associated with theconventional technology. However, since droplets of increasingly smallsize contain diminimous reaction volume, and since little furtheradvantage is to be gained in enhanced reaction rate and reducedover-reaction, preferably the droplets are to be controlled such thatthe diameter of the droplet is more than 0.5 times the thickness of theliquid-film associated with the conventional technology. More preferablythe droplets are to be controlled such that the diameter of the dropletis more than 1 time the thickness of the liquid-film associated with theconventional technology. While the thickness of the liquid-filmassociated with the conventional technology is a function of manyvariables including, but not limited to, temperature and viscosity ofthe liquid solvent and liquid reactant, generally the thickness of theliquid-film is in the range of 0.05 inches to 0.0001 inch. In absoluteterms the preferred average droplet diameter is in the range of 0.001 to0.2 inch.

The ways to control average droplet diameters in atomization iswell-known to the art, and it includes, but is not limited to, nozzledesign, variable nozzle characteristics, pressure of atomized material,pressure of gas if gas is used for the atomization process, and thelike.

The control of conversion within tight ranges and at desired levels iscritical to a well run process. Erratic control leads to poor chemicaland physical yields, process upsets, high purification costs, high traceimpurity levels, high recycle requirements, lost utility, and reducedplant capacity. Too low conversion results in high recycle requirements,reduced physical yield, higher unit plant investment, higher unit energyconsumption, and reduced plant capacity. Too high conversion leads toover-reaction, poor chemical yields, high purification costs, high traceimpurity levels, higher unit plant investment, and reduced plantcapacity. In this invention, multiple ways are provided to controlconversion. Conversion may be controlled at a desired level bymanipulation of variables, either alone or in combination with eachother. Some of these variables are:

Oxygen concentration in the reaction chamber.

The ratio of the concentrations of liquid solvent to liquid reactant inthe liquid feed to the reaction chamber.

The concentration of catalyst in the liquid feed to the reactionchamber.

The hold-up time of the liquid feed in the reaction chamber.

The size or diameter of the droplets in the reaction chamber.

The temperature of the droplets.

According to this invention, conversion can be controlled, for example,by regulating the oxygen concentration in the reaction chamber. This isto be done by using oxygen as the limiting reagent. In this instance,the rate of oxygen feed to the reaction chamber would be increased ordecreased as required to control conversion. Conversion isincreased--holding all other parameters constant--by increasing oxygenfeed rate, and thereby increasing oxygen concentration in the reactionchamber. Conversion is decreased--holding all other parametersconstant--by decreasing oxygen feed rate, and thereby decreasing oxygenconcentration in the reaction chamber.

Further, conversion is increased--holding all other parametersconstant--by increasing the concentration of catalyst in the liquid feedto the reaction chamber. Conversion is decreased--holding all otherparameters constant--by decreasing the concentration of catalyst in theliquid feed to the reaction chamber.

In addition, conversion is increased--holding all other parametersconstant--by increasing the hold-up time of the liquid feed in thereaction chamber. Conversion is decreased--holding all other parametersconstant--by decreasing the hold-up time of the liquid feed in thereaction chamber. Hold-up time of the liquid feed in the reactionchamber is controlled by varying the height of the gas-phase through thedroplets fall. Hold-up time is increased by increasing the height, anddecreased by decreasing the height. The height may be controlled inseveral ways. For example, it may be controlled by:

Raising or lowering the height of the droplet spray nozzle or nozzles.

Raising or lowering the height of a liquid pool at the liquid level atthe end of the vertical reaction chamber. The height of the liquid poolcan be determined and controlled by a variety of ways well known to theart.

Also, conversion is increased--holding all other parameters constant--bydecreasing the size of the liquid droplets in the reaction chamber.Conversion is decreased--holding all other parameters constant--byincreasing the size of the liquid droplets in the reaction chamber.Droplet size inversely affects conversion by controlling oxygen masstransfer into the liquid reaction media. Since the ratio of surface areato volume for a spherical droplet is inversely proportional to thediameter of a droplet, and since oxygen transport from the gas-phase isdirectly proportional to the surface area of a droplet, then the ratioof oxygen mass transport to the liquid volume contained in a dropletvaries inversely with the diameter of the droplet. Therefore, therelative oxygen mass transfer for larger droplets is smaller than thatfor smaller droplets, and conversion is correspondingly reduced when allother parameters are held constant.

Because reaction rates are faster at higher temperatures, in thisinvention, conversion is increased--holding all other parametersconstant--by increasing the temperature of the liquid droplets.Conversion is decreased--holding all other parameters constant--bydecreasing the temperature of the liquid droplets in the reactionchamber.

According to this invention, the heat of reaction may be removed fromthe liquid reaction mass as vaporized liquid reactant and vaporizedliquid solvent. These vaporized materials may be condensed eitheroutside or inside the reaction chamber as it will be discussedhereinbelow. Removal of heat inside the reaction chamber may beconducted for example by using condensation sprays, or condensationsurfaces, or a combination thereof.

It should be stressed that internal condensation may take place eitheroutside or inside the reaction chamber, as illustrated later. Internalcondensation is condensation which takes place within the system, beforethe pressure is relieved. Internal or external (outside the pressurizedsystem) should not be confused with inside (inside the reaction chamber)and outside (outside the reaction chamber) conversion.

In the case of condensation sprays, a portion of recycled liquid may becooled in a heat exchanger, external to the reaction chamber, and besprayed into the interior reaction chamber walls, or into the gas-phaseof the reaction chamber, or both. In the case where said spray isdirected onto the reaction chamber wall, and in the instance wherereaction products are relatively insoluble in said spray, then streamsafter filtering out the reaction products are preferable. The absence ofcatalyst in this case is also important, because this absence and therelatively cold nature of the incoming streams act to prevent reactionin said spray on the interior wall of the reaction chamber. In the casewhere reaction products are relatively insoluble, this absence ofreaction prevents the highly undesirable accumulation of solids on thissurface. Condensation spray is effective because hot, condensible gasesinside the reaction chamber condense on the cool, liquid surface. Theamount of condensation induced in this manner may be controlled byregulating the flow rate, temperature, and position of the condensationspray. Increasing the flow rate, decreasing the temperature, andcontrolling the condensation spray so as to increase its liquid surfacearea act individually or in combination to increase the rate ofcondensation of the vaporized liquid containing the reactant andvaporized liquid solvent; the converse is also true.

Furthermore, in the case of condensation sprays, this invention providesboth the means to control the liquid surface area of the condensationspray, and the means to prevent excessive contact of the reaction liquidspray with the condensation spray. Where condensation spray is directedagainst the side of the reaction chamber wall, the condensation surfacearea may be effectively controlled by manipulating the impingementposition of the condensation spray nozzles on the side of the reactionchamber wall. Directing this spray higher up the side of the reactionchamber wall increases the condensation surface area. Conversely,directing it lower decreases the condensation area. Where thecondensation spray is directed into the gas-phase of the reactionchamber, the condensation surface area may be effectively controlled bymanipulating the size and amount of the droplets. Since the ratio ofsurface area to volume for a spherical droplet is inversely proportionalto the diameter of a droplet, and since the cumulative volume of all ofthe droplets sprayed into the reaction chamber is fixed for a given flowrate, then the surface area may be easily and precisely increased--whenall other parameters are held constant--by decreasing the droplet size.The converse is also true. Droplet size can be easily controlled usingtechniques well known to the art.

Furthermore, in the case of condensation sprays, it is critical toprevent excessive contact of the reaction liquid spray with thecondensation spray. This is true because the condensation spray may notcontain catalyst and is deliberately cooled well below the reactiontemperature of the liquid reaction media. Excessive mixing of these twosprays could result in a significant reduction in condensationefficiency, reaction rate, or both. Excessive mixing is prevented in thefirst instance by positioning the spray nozzles so as to direct thecondensation spray against the reaction chamber wall, and the liquidreaction spray into the gas-phase of the reaction chamber in a mannerwhich minimizes wall contact. In the second instance, excessive mixingis prevented by selecting a spray nozzle for the condensation spraywhich produces a very small diameter droplet. This technique iseffective because very small droplets do not readily mix with similar,smaller, or larger sized droplets, thereby preventing the undesiredcontact with the liquid reaction spray. Furthermore, producing a verysmall condensation spray droplet is highly efficient, from thestandpoint of the desired condensation of vaporized liquid reactant andvaporized liquid solvent, because it increases the condensation surfacearea.

In the case of condensation sprays, and in the second instance where thecondensation spray is directed into the gas phase of the reactionchamber and where excessive mixing is prevented by selecting a spraynozzle for the condensation spray which produces a very small diameterdroplet, this invention provides a reaction system in which the liquidcontents of the reaction chamber are comprised of two different droplettypes: both types simultaneously occupy the same reaction environmentand each is in close proximity to the other, but each type remainsseparate, each contains different concentrations of liquid solvent andliquid reaction chemicals, each type is at significantly differenttemperatures, and each performs different functions (namely, eithercondensation or reaction).

In the case where vaporized liquid reactant and vaporized liquid arecondensed inside the reaction chamber on metal surfaces, this may beaccomplished in the first instance by externally cooling the reactionchamber walls with an external cooling jacket through which iscirculated a cooling medium, like cooling water; or, in the secondinstance, by providing a cooling coil or other cooling surface insidethe reaction chamber through which is circulated a cooling medium, likecooling water. In the first instance, condensation occurs inside thereaction chamber when condensible gases come into contact with theexternally cooled reaction chamber walls. The walls cooled by thismethod may be the vertical sides of the reaction chamber, or the top, orthe bottom, or a combination thereof. In the second instance,condensation occurs when the condensible gases come into contact withthe internal cooling coils or other cooling surfaces inside the reactionchamber.

According to this invention, non-condensible gases are swept away fromthe condensation surfaces (regardless of whether these condensationsurfaces are the ones produced by the use of condensation sprays or bymetal surfaces) by gaseous eddie currents inside the reaction chamber.These eddie currents may be induced by the combined liquid sprays insidethe reaction chamber. The efficient removal of the non-condensible gasesfrom the condensation surfaces is critical, because unless this is done,the condensation surfaces become blanketed by the non-condensibles, andthe desired condensation is greatly diminished.

As already discussed, according to this invention, non-condensiblereaction by-product gases may be purged from the reaction chamberthrough an overhead gas outlet or they may be purged out the bottom ofthe reaction chamber. In the former case, the small diameter liquidreaction droplets, or the small diameter liquid reaction droplets alongwith very small condensation spray droplets, produced according to themethods of this invention, fall to the bottom of the reaction chamber,where they coalesce and exit the reaction chamber. In the latter case,the small diameter liquid reaction droplets, or the small diameterliquid reaction droplets along with the very small condensation spraydroplets, either fall to the bottom of the reaction chamber and coalescethere, or are swept by the non-condensible purge gases into a swirlingvortex at the bottom of the reaction chamber and, thereby, are broughtinto extremely close proximity with the liquid, where they coalesce, asit will be discussed in more detail later. The extremely close contactso induced is sufficient to coalesce the small diameter liquid reactiondroplets, or the small diameter liquid reaction droplets along with thevery small condensation droplets, from the gas purge into the liquidphase. In both cases, therefore, the liquids exiting the bottom of thereaction chamber may remove both the reaction liquid spray, and thecondensation spray, if present, from the reaction chamber.

As aforementioned, the controller points the transient conversion in thedroplets toward a predetermined conversion range. By this, it is meantthat the controller is adapted to change one or more parameters, such asthe preferable parameters dealt with as examples below, so that saidchange will favor a respective change in the transient conversion towardthe predetermined range.

Depending on the reaction characteristics, some parameters or variablesmay be more or less effective in causing changes to the transientconversion. It is possible in some occasions that changes in oneparameter may not be capable to bring the transient conversion withinthe predetermined range. In such cases, the controller is preferablyadapted or programmed to select and change one or more additionalvariables in order to receive the desired result.

In the description of the preferred embodiments of the instantinvention, it is assumed for purposes of clarity that the particularvariable under consideration is capable by itself to bring the transientconversion within the predetermined range. This is generally true,provided that for a particular reaction, conducted in the devices and bythe methods of this invention, the most efficient variable(s) has beenselected to be controlled by the controller. It should be understood,however, that the selection of one or more additional variables is wellwithin the scope of this invention.

It is important to note that according to this invention, appropriateoverriding program rules may be used to overide the normal program ofthe controller, especially in occasions involving safety matters. Forexample, the temperature in the reaction chamber may preferably bemonitored, and if it is found to start rising at a rate faster than apreset value, the controller should cause commensurate changes in one ormore variables at a high enough rate to offset said rise timely, beforeany catastrophic outcome.

In addition, monitoring carbon monoxide and carbon dioxide in theoff-gases is a prudent precaution, since unexpected or higher thannormal amounts of carbon monoxide and/or carbon dioxide signify poorlycontrolled or uncontrolled oxidation. Similar overriding rules appliedby the controller help in preventing poor yields, conversions, and evenexplosions.

In the following description, the droplets have an average dropletdiameter and they are produced at a desired first flow rate, the gasflows at a second flow rate, the droplets may contain volatileingredients volatilizing at a volatilization rate, the first liquidcontains a first reactant at a first content, the gas contains a secondreactant, such as an oxidant for example, at a second content. The ratioof the reactant to the inert or other gas determines the content ofsecond reactant in the gas.

Also, in the following description, transient conversion is theconversion of first reactant to reaction product as droplets of firstliquid travel from the atomizer to the sample collector. It should beunderstood that information regarding the amounts of first reactant andreaction product, if present, are monitored in the first liquid and theyare provided to the computerized controller through the conversionmonitor along with information regarding the percent moles of reactionproduct in the sample collector. This whole information is collectivelycalled transient conversion information. The analyses and/orcomputations from different lines are conducted by well known to the arttechniques, and they have been omitted from the Figures for purposes ofclarity. More specifically the transient conversion is defined as theratio (O² -O¹)x100/R¹ xn, where:

O¹ is the percent moles of reaction product in the first liquid;

O² is the percent moles of reaction product as provided to theconversion monitor by the sample collector;

R¹ is the percent moles of first reactant in the first liquid; and

n is the number of moles reaction product produced when one mole offirst reactant is completely converted to said reaction product.

The inventors have recognized that in the case of atomizing reactors,transient conversion is of essence for controlling reactions, and notjust the overall conversion over the whole process, as employed so farin the art. Control of transient conversion, not only helps in improvingthe yield, but in addition, in oxidations for example, it helps inavoiding complete oxidation, combustion, or even explosion.

In one embodiment of the present invention, better shown in FIG. 1,there is depicted a device 10 for preparing a reaction product from afirst liquid containing a first reactant and a gas containing a secondreactant. The device 10 comprises a reaction chamber 12, which chamberhas an upper end 14, a lower end 16 and a reaction zone 18. The reactionchamber 12 also has a wall having an inside surface 21. The chamber 12is preferably of cylindrical shape turning to conical at the vicinity ofthe lower end 16, and finally leading to a liquid outlet 22 connected toan outlet line 24. The outlet line 24 leads to a separator 15 where thereaction products are separated from reactants following line 13, andunreacted reactants, usually containing various amounts of reactionproducts, solvents, catalysts, and other adjuncts, return to arecirculation tank 19 through line 11. The separator may be as simple adevice as a filter, or as complicated as a battery of tanks, washers,extractors, distillation columns, etc., suitable to each particularcase. A by-pass line 50, connected to the system through a by-pass valve52 is used to by-pass the separator 15, if so desired.

At the vicinity of the upper end 14 of the reaction chamber 12, there isprovided a gas outlet 23 leading to an outlet gas line 25.

There is also provided a liquid dispensing ring 44 on the wall 20 of thereaction chamber 12. The liquid dispensing ring 44 is connected to line11', which provides liquid, preferably recovered. The ring 44 is adaptedto distribute said liquid substantially uniformly on the inside surface21 of the wall 20 in the form of a thick film or curtain 45.

The reaction chamber 12 is preferably adapted to withstand suchtemperatures and pressures, which are appropriate for the reactionconditions in the reaction chamber 12, and be suitable for the reactantsand reaction products. Such materials and construction characteristicsare well known to the art. For example, depending on the particularreaction, carbon steel, stainless steel, or Hastalloy may be required.In addition, the inside surface 21 may be protected by coatings orlinings of vitreous or other materials.

Inside the reaction chamber 12, and preferably in the vicinity of theupper end 14, there is disposed an atomizer 26, preferably comprising aplurality of nozzles 27. The atomizer 26 is preferably of the airlesstype (does not need an atomizing gas for its operation). Airlessatomizers are well known to the art. The atomizer 26 may be steady at acertain position of the reaction chamber 12, or it may be movable,preferably in an up/down mode. A driving mechanism 28, supporting theatomizer 26 is preferably connected to the reaction chamber 12 in thevicinity of the upper end 14. The driving mechanism 28 may be ahydraulic or pneumatic cylinder, or it may be of mechanical nature, suchas one of the screw type, for example. It is mainly important that thedriving mechanism 28 is adapted to move the atomizer 26 in a preferablyup/down mode in a controllable manner, and without introducing leaks tothe reaction chamber 12.

A gas inlet 34, preferably located in the vicinity of the lower end 16of the reaction chamber 12, is connected to a gas inlet feed line 36,which provides the gas containing the second reactant.

In the vicinity of the lower part 16 of the reaction chamber 12, thereis provided a sample collector 30, which is adapted to collect dropletsof liquid and transfer them preferably as a miniature stream of liquidto a conversion detector (the word detector according to the presentinvention includes the meaning of monitor) 32 through sample line 33.The conversion detector 32 may also monitor the amount of first reactantand the amount of the reaction product in the recirculation tank 19through a sample line 17. This information along with information on thenature and quantity of what is added in line 41, for example, canaccurately determine the amounts of reaction product and first reactantgoing to the atomizer 26.

A heat exchanger 38 is adapted to provide recirculated reactant mixturefrom the recirculation tank 19 to a replenishment receptacle 40, throughinlet line 39. The replenishment receptacle 40 is also provided withfresh reactants, catalysts, solvents, and other adjuncts necessary forthe reaction in each particular case through inlet line 41. Thereplenishment receptacle 40 may be a container comprising temperaturecontrol (not shown) and a high pressure pump (not shown), which providesmixture made in the receptacle 40 to the nozzles 27 of the atomizer 26through line 42 at a desired atomization temperature. Line 42 has aflexible, preferably coiled portion 43, so that it can follow anymovements of the atomizer 26.

The device 10 also comprises a controller 35, preferably computerized,which is fed information regarding transient conversion of reactants toreaction product from conversion detector 32 through input line 31, andit controls heat exchanger 38 through output line 27, the drivemechanism 28 through output line 29, and the replenishment receptacle 40through output line 37.

The monitor or detector 32 may be any instrument which is adaptable todetect the reaction product or products. It may, for example, comprise achromatography apparatus, a UV spectrograph, an IR spectrograph, avisible light spectrograph, a mass spectrometer, a NMR instrument, aconductivity monitor, an ionization detector, a flame detector, anyother suitable instrument, or a combination thereof.

In the case that the reaction product is a non-volatile acid, it ispreferable that the monitor or detector 32 comprises a HPLC (HighPressure/Performance Liquid Chromatography instrument) in combinationwith a UV monitor. It is also preferable that the HPLC instrument hasmore than one columns, so that if the separation time in a column islonger than desired, consecutive samples are introduced in differentcolumns and a multiplicity of separations are conducted in parallel sothat the interval between monitoring consecutive samples falls withindesired limits. If it is desired to also analyze also non-polar organicmoieties, it would be preferable to also include a gas chromatographicmonitor or detector coupled with an appropriate monitor, such as anionization monitor, for example.

The method and the devices of the instant invention are particularlysuitable for oxidation reactions of organic compounds, wherein the majorportion of the reaction product is an oxidation product different thanCO, CO₂, or a mixture thereof. One of the reasons why this is so, isthat, due to the intricate criticalities of the present invention, thereaction rates, reaction homogeneity, yield, and other importantproperties are considerably improved, while in the absence of saidcriticalities complete oxidation to CO/CO₂ would take place. Actually,the same conditions of atomization without said criticalities, arepresently used in combustion engines of automobiles and other devices,to substantially completely oxidize (combust or burn in other words)organic compounds such as gasoline to a mixture of CO/CO₂.

In contrast, according to the present invention, if for example, thefirst reactant is cyclohexane, the major portion of the oxidationproduct may be substantially cyclohexanol, cyclohexanone,cyclohexylhydroperoxide, caprolactone, adipic acid, the like, andmixtures thereof. Organic acids are preferable oxidation products.

The operation of this, as well as the other embodiments of the instantinvention, will be discussed for any reaction, such as non-destructiveoxidation for example, encompassed by the claims, and at the same timeit will be exemplified, by using cyclohexane as a first reactant, oxygenas the second reactant in the gas, and adipic acid as the reactionproduct.

In operation of this embodiment, a first liquid containing the firstreactant, cyclohexane for example, enters the reaction chamber 12through line 42 in a manner that it is atomized by the atomizer 26 andnozzles 27, in a manner to form a plurality of droplets 48. The firstliquid enters the atomizer at a desired atomization temperature, whichin the case of cyclohexane is preferably in the range of 50°-1500° C.,more preferably in the range of 80°-130° C., and even more preferably inthe range of 90°-120°. Atomization temperature of the first liquid isthe temperature of the liquid just before it is atomized. Thetemperature of the just formed droplets may be the same or differentthan the atomization temperature. In the case of cyclohexane, the firstliquid also preferably contains a solvent, such as acetic acid, forexample, a catalyst, such as a cobalt compound, soluble in the firstliquid, for example, and an initiator, such as cyclohexanone,methylethylketone, acetaldehyde, the like, and mixtures thereof, forexample. The pressure in the case of oxidation of cyclohexane to adipicacid should preferably be high enough to maintain the cyclohexane,solvents, initiators, etc., substantially in the liquid state. Althoughpressures even in excess of 1,000 psia are possible, pressures in therange of 100 to 400 psia are preferable, and pressures in the range of150 to 300 psia more preferable.

The atomizer 26 is initially preferably placed, by the drive mechanism28, at a low position close to the lower end 16 of the reaction chamber12 (although in FIG. 1 the atomizer 26 happens to have a position in thevicinity of the upper end 14 of the reaction chamber 14), at a distancefrom a mass of a second liquid 54, which has a second surface 56, andwhich is collected and disposed of at the lower end 16 of the reactionchamber 12 through liquid outlet 22. The second liquid is a combinationof coalesced droplets 48 and liquid from the thick film or curtain 45.The distance between the nozzle of the atomizer which is closest to thesurface 56 of the mass 54, and the surface 56 of the mass of the secondliquid 54 is defined as the atomization distance. If the second liquid54 has been removed completely from the reaction chamber 12, theatomization distance is defined as the distance between the nozzle ofthe atomizer which is closest to the point where the liquid outlet 22meets the reaction chamber, and that point. The atomization distance atthe beginning of the operation is preferably about one third to onefourth of the maximum atomization distance. The maximum atomizationdistance is the atomization distance when the atomizer is as far awayfrom the surface 56 of the second liquid mass 54 as the design of thedevice 10 and the atomizer 26 allows. The atomizer has the maximumatomization distance in FIG. 1.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane, enters the chamber 12 through the gas inlet feed line 36,in the vicinity of the lower end 16 of the chamber 12. The gas, inaddition to the second reactant, may also contain rather inert gases,such as nitrogen and/or carbon dioxide for example. Off gases mixed withvapors of reactants, solvents, mist, and the like exit the reactionchamber through outlet gas line 25 and are treated as it willexemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 26,they start reacting with the second reactant, which is oxygen forexample. The second liquid 54 is removed, preferably continuously,through the liquid outlet 22, and it is pumped (pump not shown) throughliquid outlet line 24 to a separator 15, where the reaction product,adipic acid for example, is separated from the liquids by techniqueswell known to the art. In some occasions, other by-products of thereaction may also be removed in the separator, if so desired. Reactants,solvents, catalysts, and the like, return through line 11 to therecirculation tank 19.

Part of the second liquid, after the above product and/or by-productremoval treatment, may be directed to the liquid dispensing ring 44,through line 11', if so desired, where it is dispensed in the form ofthe thick film or liquid curtain 45, and covers the inside surface 21 ofthe wall 20 of the reaction chamber 12. The temperature of this film,when it is dispensed from the dispensing ring 44 is arranged to be lowerthan the atomization temperature. In the case of cyclohexane to adipicacid, for example, it is preferably in the range of 20° to 80° C., andmore preferably in the range of 20° to 40° C. At this lower temperature,no appreciable reaction takes place, and any droplets coalescing ontothe film do not have much effect to the process. Any solid productswhich are insoluble in the droplets are washed down by the liquidcurtain 45, and they form the second liquid 54 along with the coalesceddroplets 48, as already mentioned. Thus, no sticking of solids takesplace on the inside surface 21 of the wall 20. It should be noted thatunrecycled liquids, which might be just solvents, or just reactants withor without catalysts or other adjuncts, or other liquids, or anycombination thereof, may replace or supplement the recycled liquidcoming from line 11'. If so desired, the second liquid transported inline 24 may by-pass the separator 15 through by-pass valve 52 andby-pass line 50 either partially or totally. This option may beutilized, especially at the beginning of the operation, if the transientconversion is under a desired pre-coalescing transient conversion level.

Measures are taken for the level or surface 56 of second liquid 54 notto move over the point at which the sample collector 30 is positioned,to prevent flooding of the sample collector 30 with second liquid 54,which will produce false sampling. Monitoring a liquid level is verywell known to the art and may be conducted with any suitable type of"liquid level monitor", available in the market. The liquid levelmonitor is then arranged to control the supply of liquids entering thereaction chamber 12 as curtain 45 though line 11', as droplets throughthe atomizer 26, or exiting the reaction chamber 12 as second liquid 54through outlet liquid line 24, or any combination thereof, so as to keepthe level or surface 56 of the second liquid mass 54 within desiredlimits under the sample collector 30. Such an arrangement is verysimple, and it is not shown in FIG. 1 for clarity purposes. Highersupply of liquids through line 11' and the atomizer will cause the levelof surface 56 to be raised, while lower supply will have the oppositeeffect. Similarly, higher removal rate through line 24 will cause thelevel of or surface 56 to be lowered, while lower removal rate will havethe opposite effect.

A part of the droplets 48 fall into the sample collector 30, just abovethe surface 56 of the second liquid mass 56, from where, they aredirected to the conversion detector or monitor 32, to be analyzedregarding transient conversion. If solids are present in the droplets,care should be taken to prevent clogging of liquid transporting lines byuse of appropriate dilution, and the like. As aforementioned, in thecase of adipic or other acid formation, it is preferable that themonitor 32 comprises a chromatography apparatus, which more preferablyis a High Performance (or Pressure) Liquid Chromatography apparatus(HPLC). This apparatus, as also mentioned earlier, may preferably havean adequate number of columns, so that it is capable of making arespective number of overlapping determinations of the reaction productpresent in the droplets just before they coalesce into the mass of thesecond liquid 54, so that the transient conversion of the first reactantto reaction product is checked as frequently as desired in eachparticular case. If the column, for example, separates the reactionproduct in 8 minutes, and the desired interval between determinations is2 minutes in a particular case, four columns are needed.

Sampling of the liquid in the recirculation tank 19, may also bedesirable, and it may be carried out in the same detector 32, throughline 17, or by means of another detector (not shown).

The information obtained in the conversion detector or monitor 32 is fedto computerized controller 35 through its input line 31, where it isprocessed by well known to the art techniques. The controller 35controls the heat exchanger 38 through its output line 46, which alongwith the temperature of the liquids provided through line 41, determinesthe temperature in the replenishment receptacle 40, which temperature issubstantially the same as the atomization temperature for all practicalpurposes. Controller 35 through its output line 37, controls the feedrate of first liquid through line 42. In addition, controller 35,through its output line 29, controls the drive mechanism 28.

If the transient conversion is above a range called according to thisinvention "pre-coalescing transient conversion range" because itrepresents the transient conversion just before the droplets coalesce onto the second liquid 54, the drive mechanism 28 is ordered by thecontroller 35 to lower the level of atomizer in a manner that theatomization distance, as defined above, decreases. The change ofatomization distance is preferably conducted in increments, preferablyin the range of 10 to 50% of the atomization distance at the particulartime, and more preferably in the range of 10 to 30%. However, otherranges may be more appropriate, depending on the particular conditions,materials, previous determination, and the like. For example, if a 10%decrease in atomization distance is found not to have an appreciableresult, the following increment may be 30%, for example. On the otherhand, if a 10% decrease in the atomization distance results in anoverwhelming change in transient conversion, the next increment may be5%, for example, until the conversion falls within the desirable range,and preferably in the most desirable range. It should be pointed outagain, however, that the desirable ranges may change, depending onmaterials, conditions, etc. The distance between the sample collector 30and the level or surface 56 of the second liquid mass 54 is preferablyin the range of 5-10% of the maximum atomization distance

In the case of oxidation of cyclohexane to adipic acid, for example, thepreferred pre-coalescing transient conversion range is 5-80%, morepreferably 10-70%, and even more preferably 20-60%.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acidunder certain conditions), it continues to be monitored with a goal inmost cases to stay somewhere in the vicinity of the middle value of saidmost desired range (about 40% for example). Continuous monitoring andcontrol are highly desirable, since the conditions in the reactionchamber may vary, causing changes in the transient conversion values.

It should be noted that if the reaction is very slow for some reason, orif so desired, partial or total recirculation (not shown) directly fromline 24 to line 42 is advisable, with or without additional feeding ofline 42 from replenishment receptacle 40.

The pre-coalescing conversion can be also calculated or measured fromsamples of the second liquid, after taking into account any factorswhich change the concentration of the reaction product in the droplets.

In another embodiment of the present invention, better shown in FIG. 2,the reaction chamber 112 is provided with an atomizer 126 in thevicinity of its upper end 114, and a sample collector 130 positioned inthe vicinity of its lower end 116. There is also provided asupplementary heat exchanger 158 and a temperature measuring device,such as a thermocouple 160, for example. The liquid dispensing ring 144is shown at the beginning of the conical portion of the reactor, but itmay take any position on the wall of the reactor, or it may be omittedall together. The same holds true for all embodiments of the presentinvention. The sample collector 130 is connected to the conversionmonitor or detector 132 through line 133 for providing samples ofdroplets 148 trapped in the collector just (and coalesced, of course inthe collector) before they coalesce onto the second liquid mass 154. Thethermocouple 160 and the conversion monitor or detector 132 areconnected, preferably electrically, to the controller 135 through inputlines 160' and 131, respectively. In turn, the controller 135 isconnected, preferably electrically, to the supplemental heat exchanger158 through output line 158' in order to control said supplemental heatexchanger 158. For purposes of clarity, basically only the elements ofthe device 110, which illustrate this embodiment and its operation, areshown.

In operation of this embodiment, the first liquid containing the firstreactant, cyclohexane for example, enters the reaction chamber 112through line 142 in a manner that it is atomized by the atomizer 126, ina manner to form a plurality of droplets 148.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane, enters the chamber 112 through the gas inlet feed line 136,in the vicinity of the lower end 116 of the chamber 112. The gas, inaddition to the second reactant, may also contain rather inert gases,such as nitrogen and/or carbon dioxide for example. Off gases mixed withvapors of reactants, solvents, mist, and the like exit the reactionchamber through outlet gas line 125 and are treated as it willexemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 126,they start reacting with the second reactant, which is oxygen forexample. The second liquid 154 is removed, preferably continuously,through the liquid outlet line 124 as in the previous embodiment.

Part of the second liquid, after removal of the reaction product and/orby-products, may be directed to the liquid dispensing ring 144, throughline 111', if so desired, where it is dispensed in the form the thickfilm or liquid curtain 145, as in the previous embodiment.

A part of the droplets 148 fall into the sample collector 130, fromwhere, they are directed to the conversion detector or monitor 132, tobe analyzed regarding transient conversion.

The information obtained in the conversion detector or monitor 132 isfed to computerized controller 135 through its input line 131, where itis processed by well known to the art techniques. Also, the atomizationtemperature from thermocouple 160 is fed to the computerized controller135. The controller 135 controls the heat exchanger 158 through itsoutput line 158'.

If the transient conversion is above the pre-coalescing transientconversion range, as earlier defined, the heat exchanger is ordered bythe controller 135 to lower the atomization temperature, monitored bythermocouple 160. Similarly, if the transient conversion is under the"pre-coalescing transient conversion range", according to thisinvention, the heat exchanger is ordered by the controller 35 toincrease the atomization temperature. The upper and lower limits of theatomization temperature depend on the reactants, conditions of thereaction, and the like. For example, in the case of oxidation ofcyclohexane to adipic acid, the upper limit should preferably bemaintained not higher than 170° C., and more preferably not higher than150° C., while the lower limit should preferably maintained not lowerthan 50° C., and more preferably not lower than 70° C.

The change of atomization temperature is preferably conducted inincrements, preferably in the range of 5 to 10% of the atomizationtemperature at the particular time.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acidfor example under certain conditions), it continues to be monitored witha goal in most cases to stay somewhere in the vicinity of the middlevalue of said most desired range (about 40%, for example). As in theprevious embodiment continuous monitoring and control are highlypreferable, since the conditions in the reaction chamber may vary,causing changes in the transient conversion values.

In a different embodiment of the present invention, better shown in FIG.3, the reaction chamber 212 is provided with an atomizer 226 in thevicinity of its upper end 214, and a sample collector 230 positioned inthe vicinity of its lower end 216. There is also provided a pressurizingpump 263 communicating with the reaction chamber 212 through line 236, aflow meter 266 in the line 236, a gas mixing valve 268 connected on oneside to an second reactant feed line 247 and an other gas line 249, anda pressure measuring device, such as a pressure gauge 262, for examplefor monitoring the pressure inside the reaction chamber 212. The liquiddispensing ring 244 is shown at about the middle of the wall of thereaction chamber 212, but it may take any position on the wall, or itmay be omitted all together. The sample collector 230 is connected tothe conversion monitor or detector 232 through line 233 for providingsamples of droplets 248 trapped in the collector, just (and coalesced,of course, in the collector) before they coalesce onto the second liquidmass 254. The pressure gauge 262, the flow meter 266, and the conversionmonitor or detector 232 are connected, preferably electrically, to thecontroller 235 through input lines 262', 266', and 231, respectively. Inturn, the controller 235 is connected, preferably electrically, to thepressurizing pump 263 through output line 263', to the gas mixing valve268 through output line 268', and to valve 264 through output line 264'.The controller 235 is adapted to control the pressurized pump 263, thegas mixing valve 268, and the valve 264. For purposes of clarity,basically only the elements of the device 210, which illustrate thisembodiment and its operation, are shown.

In operation of this embodiment, the valve 264 is initially closed orturned to the off position. The gas mixing valve 268 is regulated todeliver a desired ratio of second reactant to inert gas (which ratiodetermines the content of second reactant in the total gas, definedearlier as the second content) to the pressurizing pump 263, obtainedfrom lines 247 and 249, respectively. The pressurizing pump is thenturned on until the desired pressure is attained in the reaction chamber212. In sequence, with the pressurizing pump still on, the valve 264 isopened to such a degree that the desired pressure is maintained in thereaction chamber. If the flow rate (second flow rate being the flow rateof the gas, as defined above), as measured from the flowmeter 266, istoo high, the pump is turned to a lower speed and the valve 264 isturned to a less open position in a manner to maintain the desiredpressure at a lower second flow rate. This is continued until both thepressure and second flow rate attain desired values. If the second flowrate, as measured from the flowmeter 266, is too low, the pump is turnedto a higher speed and/or the valve 264 is turned to a more open positionin a manner to maintain the desired pressure at a higher second flowrate. This is continued until both the pressure and the second flow rateattain desired values.

After both pressure and the second flow rate have attained their initialdesired values, the first liquid, after having been heated to theatomization temperature as described before, which liquid contains thefirst reactant, cyclohexane for example, enters the reaction chamber 212through line 242 in a manner that it is atomized by the atomizer 226,and forms a plurality of droplets 248.

At the same time that the first liquid is being atomized, the mixed gascontaining the second reactant, preferably oxygen in the case ofcyclohexane, enters the chamber 212 through the gas inlet feed line 236,in the vicinity of the lower end 216 of the reaction chamber 212. Thedesired ratio of the gases (defining the second content as discussedearlier) depends on the reaction and conditions, and it may have anyvalue suitable for the circumstances. In most cases the preferablesecond reactant is oxygen and the other gas is an inert gas, such asnitrogen or carbon dioxide, for example. Off gases mixed with vapors ofreactants, solvents, mist, and the like exit the reaction chamber 212through outlet gas line 225, and are treated as it will be exemplifiedat a later section.

As the droplets fall in a downwardly direction from the atomizer 226,they start reacting with the second reactant, which is oxygen forexample. The second liquid 254 is removed, preferably continuously,through the liquid outlet line 224 as in the previous embodiments.

Part of the second liquid, after removal of the reaction product and/orby-products, in the separator 15 shown in FIG. 1, may be directed to theliquid dispensing ring 244, through line 211', if so desired, where itis dispensed in the form the thick film or liquid curtain 245, as in theprevious embodiments.

A part of the droplets 248 fall into the sample collector 230, fromwhere, they are directed to the conversion detector or monitor 232, tobe analyzed regarding transient conversion.

The information obtained in the transient conversion detector or monitor232 is fed to computerized controller 235 through its input line 231,where it is processed by well known to the art techniques. Also, thepressure within the reaction chamber from gauge 262, and the flow rateof gases (second flow rate) through line 236 measured by the flow meter266 are fed to the computerized controller 235 through input lines 262'and 266', respectively. As aforementioned, the controller 235 controlsthe pressurizing pump 263 through its output line 263', valve 264through its output line 264', and gas mixing valve 268 through itsoutput line 268'.

Controlling the pressurizing pump means that the controller is adaptedto change the pressure and flow output of the pressurizing pump based ondata received from input lines 231, 266', and 262', said data beingprocessed according to a desired program. Controlling the valve 264means that it is adapted to open/close said valve 264 to a desireddegree based on data received from input lines 231, 266', and 262', saiddata being processed according to a desired program. Controlling the gasmixing valve 268 means that it is adapted to regulate said valve 268 ina manner to feed the pressurizing pump 263 with a mixture of secondreactant provided by line 247 and other (such as inert for example) gasprovided by line 249, so that the mixture has a desired weight ratio,based on data received from input lines 231, 266', and 262', said databeing processed according to a desired program. Programming computerizedcontrollers is well known to the art.

As it can be seen in FIG. 3, two elements which can determine thepressure inside the reaction chamber 212, as well as the second flowrate in this embodiment, are the pressurizing pump 263 and the valve264. Other elements in line 225, such as condensers (not shown), gasrecirculation assemblies (not shown), and the like for example, may alsoinfluence the pressure, mostly temporarily, but they have been omittedfrom FIG. 3 for purposes of clarity. They will be discussed at a latersection. The more gas the pressurizing pump dispenses to the reactionchamber 212, and the more closed the valve 264 is the higher thepressure inside the reaction chamber. The less gas the pressurizing pumpdispenses to the reaction chamber 212, and the more open the valve 264the lower the pressure inside the reaction chamber. Of course, the flowor delivery rate of gas by the pressurizing pump 263 and the degree ofopening of the valve 264 have to be coordinated in order to achieve adesired pressure inside the reaction chamber.

The data received in the computerized controller 235 may be used afterbeing processed in a number of ways, or combinations thereof, to controlthe transient conversion and maintain it within the pre-coalescingtransient conversion range.

One way is to vary the flow rate of the gas (second flow rate) enteringthe reaction chamber 212 through line 236. If the transient conversion,as measured in the transient conversion monitor or detector 232 has ahigher value than the desired pre-coalescing transient conversion range,the computerized controller 235 orders the pressurizing pump to decreasethe second flow rate as measured by the flowmeter 266. At the same time,the valve 264 is ordered by controller 235 to attain a somewhat moreclosed or restricted position so that the pressure inside the reactionchamber 212, as measured by the pressure gauge 262, tends to remainwithin the desired range. This is continued until the second flow ratehas attained a newly desired value, and pressure is within the desiredrange. If the transient conversion, as measured in the conversionmonitor or detector 232 has a lower value than the desiredpre-coalescing transient conversion range, the computerized controller235 orders the pressurizing pump to increase the second flow rate asmeasured by the flowmeter 266. At the same time, the valve 264 isordered by controller 235 to attain a somewhat more open position, sothat the pressure inside the reaction chamber 212, as measured by thepressure gauge 262, tends to remain within the desired range. This iscontinued until the second flow rate has attained a newly desired valueand the pressure is within the desired range. The second flow ratechanges (increase or decrease) from one value to a newly desired valueshould preferably be in increments, preferably in the range of 5-20% andmore preferably in the range of 5-10%. Also, changes should preferablybe ordered by the computerized controller in time intervals long enoughto contain at least one new transient conversion measurement in theconversion monitor or detector 232.

If the transient conversion under the newly attained second flow ratedoes not fall within the predetermined pre-coalescing transientconversion range, the same process is repeated until the transientconversion finally falls within the desired transient conversion range.

Another way is to vary the ratio of the second reactant to the inert orother gas entering the reaction chamber 212 through line 236. If thetransient conversion, as measured in the conversion monitor or detector232 has a higher value than the desired pre-coalescing transientconversion range, the computerized controller 235 orders the gas mixingvalve 268 to decrease said ratio. If the transient conversion, asmeasured in the conversion monitor or detector 232 has a lower valuethan the desired pre-coalescing transient conversion range, thecomputerized controller 235 orders the gas mixing valve 268 to increasesaid ratio. The ratio changes (increase or decrease) from one value to anewly desired value should preferably be in increments, preferably inthe range of 5-20% and more preferably in the range of 5-10%. Also,changes should preferably be ordered by the computerized controller intime intervals long enough to contain at least one new transientconversion measurement in the conversion monitor or detector 232.

Still a different way is to vary the pressure of the gas in the reactionchamber 212 in many occasions, where increase in pressure increasesreactivity to a substantial degree. If the transient conversion, asmeasured in the transient conversion monitor or detector 232 has ahigher value than the desired pre-coalescing transient conversion range,the computerized controller 235 orders the pressurizing pump slow down.At the same time, the valve 264 is ordered by controller 235 to attain asomewhat more open position so that the second flow rate, as measured bythe flow meter 266, tends to remain within the desired range. This iscontinued until the pressure has attained a newly desired value, and thesecond flow rate is within the desired range. If the transientconversion, as measured in the conversion monitor or detector 232 has alower value than the desired pre-coalescing transient conversion range,the computerized controller 235 orders the pressurizing pump speed up.At the same time, the valve 264 is ordered by controller 235 to attain asomewhat more closed position so that the second flow rate, as measuredby the flow meter 266, tends to remain within the desired range. This iscontinued until the pressure has attained a newly desired value, and thesecond flow rate is within the desired range. The pressure changes(increase or decrease) from one value to a newly desired value shouldpreferably be in increments, preferably in the range of 2-20% and morepreferably in the range of 5-10%. Also, changes should preferably beordered by the computerized controller in time intervals long enough tocontain at least one new transient conversion measurement in theconversion monitor or detector 232.

If the transient conversion under the newly attained pressure does notfall within the predetermined pre-coalescing transient conversion range,the same process is repeated until the transient conversion finallyfalls within the desired transient conversion range.

In another embodiment of the present invention, better shown in FIG. 4,the reaction chamber 312 is provided with an atomizer 326 in thevicinity of its upper end 314, and a sample collector 330 positioned inthe vicinity of its lower end 316. There is also provided a reactantmixing valve 369, which is adapted to mix first reactant from line 370and other liquids from line 371 in order to produce the first liquid inline 342 having a first content of first reactant. The sample collector330 is connected to the conversion monitor or detector 332 throughsample line 333 for providing samples of droplets 348 trapped in thecollector just (and coalesced, of course in the collector) before theycoalesce onto the second liquid mass 354. The conversion monitor ordetector 332 is connected, preferably electrically, to the controller335 through input line 331 for transferring transient conversioninformation. In turn, the controller 335 is connected, preferablyelectrically, to the reactant mixing valve 369 through output line 369'in order to control said reactant mixing valve 369. For purposes ofclarity, basically only the elements of the device 310, which illustratethis embodiment and its operation, are shown.

In operation of this embodiment, first reactant from line 370 and otherliquids from line 371 are mixed in proportions regulated by the reactantmixing valve 369, in order to produce the first liquid in line 342 sothat said first liquid has a first content of first reactant. Theliquids from line 371 may contain solvents, catalysts, promoters,initiators, recycled ingredients, first reactant, and the like. If theliquids from line 371 contain first reactant, the content of theseliquids in first reactant has to be taken into account in thedetermination of the first content of first reactant in line 342, sothat the reactant mixing valve 369 allows accordingly less firstreactant from line 370. The first liquid containing the first reactant,cyclohexane for example, in a first content, enters the reaction chamber312 through line 342 in a manner that it is atomized by the atomizer326, and forms a plurality of droplets 348.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane, enters the chamber 312 through the gas inlet feed line 336,in the vicinity of the lower end 316 of the chamber 312. The gas, inaddition to the second reactant, may also contain rather inert gases,such as nitrogen and/or carbon dioxide, for example. Off gases mixedwith vapors of reactants, solvents, mist, and the like exit the reactionchamber 312 through outlet gas line 325 and are treated as it willexemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 326,they start reacting with the second reactant, which is oxygen forexample. The second liquid 354 is removed, preferably continuously,through the liquid outlet line 324 as in the previous embodiments.

A part of the droplets 348 fall into the sample collector 330, fromwhere, they are directed to the conversion detector or monitor 332, tobe analyzed regarding transient conversion.

The information obtained in the conversion detector or monitor 332 isfed to computerized controller 335 through its input line 331, where itis processed by well known to the art techniques. The controller 335controls the reactant mixing valve through its output line 369'.

If the transient conversion is above the pre-coalescing transientconversion range, as earlier defined, the reactant mixing valve 369 isordered by the controller 335 to increase the first content byincreasing the ratio of the first reactant from line 370 to liquids fromline 371. Similarly, if the transient conversion is under the"pre-coalescing transient conversion range", according to thisinvention, the reactant mixing valve 369 is ordered by the controller335 to decrease the first content by decreasing the ratio of the firstreactant from line 370 to liquids from line 371.

The change of first content is preferably conducted in increments,preferably in the range of 5 to 10% of the first content at theparticular time.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acid,for example, under certain conditions), said transient conversioncontinues to be monitored with a goal in most cases to stay somewhere inthe vicinity of the middle value of said most desired range (about 40%,for example). As in previous embodiments, continuous monitoring andcontrol are highly preferable, since the conditions in the reactionchamber may vary, causing changes in the transient conversion values.Valves regulating ratios of liquids, and controlled by computerizedcontrollers according to a desirable program are well known in the art.

In still another embodiment of the present invention, better shown inFIG. 5, the reaction chamber 412 is provided with an atomizer 426 in thevicinity of its upper end 414, and a sample collector 430 positioned inthe vicinity of its lower end 416. The atomizer 426 may be operable bygas or preferably without the need of gas (usually referred to as"airless" in the art). The atomizer 426 of this embodiment is adapted tocontrol at will the droplet size or diameter through a regulator 472.Such atomizers are well known in the art. For example, droplet diametermay change by changing the pressure of the liquid to be atomized,changing the orifice size, changing the frequency and/or intensity inthe case of ultrasonic or other pulsation operated atomizers, changingthe pressure of the gas in the case of gas operated atomizers, changingthe rotation of the speed in the case of centrifugal atomizers, etc. Forthe purposes of the instant invention, the regulator 472 represents anymechanism well known to the art, which is adapted to controllably changeany variable parameter of the atomizer which controls average diameterof the droplets.

The sample collector 430 is connected to the conversion monitor ordetector 432 through sample line 433 for providing samples of droplets448 trapped in the collector just (and coalesced, of course in thecollector) before they coalesce onto the second liquid mass 454. Theconversion monitor or detector 432 is connected, preferablyelectrically, to the controller 435 through input line 431 fortransferring transient conversion information. In turn, the controller435 is connected, preferably electrically, to the regulator 472 throughoutput line 472' in order to control said regulator 472. For purposes ofclarity, basically only the elements of the device 410, which illustratethis embodiment and its operation, are shown.

In operation of this embodiment, the first liquid containing the firstreactant, cyclohexane for example, enters the reaction chamber 412through line 442 in a manner that it is atomized by the atomizer 426,and forms a plurality of droplets 448.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane, enters the chamber 412 through the gas inlet feed line 436,in the vicinity of the lower end 416 of the chamber 412. The gas, inaddition to the second reactant, may also contain rather inert gases,such as nitrogen and/or carbon dioxide, for example. Off gases mixedwith vapors of reactants, solvents, mist, and the like exit the reactionchamber 412 through outlet gas line 425 and are treated as it willexemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 426,they start reacting with the second reactant, which is oxygen forexample. The second liquid 454 is removed, preferably continuously,through the liquid outlet line 424 as in the previous embodiments.

A part of the droplets 448 fall into the sample collector 430, fromwhere, they are directed to the conversion detector or monitor 432, tobe analyzed regarding transient conversion.

The information obtained in the conversion detector or monitor 432 isfed to computerized controller 435 through its input line 431, where itis processed by well known to the art techniques. The controller 435controls the regulator 472 through its output line 472'.

If the transient conversion is above the pre-coalescing transientconversion range, as earlier defined, the regulator 472 is ordered bythe controller 435 to increase the average diameter of the droplets.Similarly, if the transient conversion is under the "pre-coalescingtransient conversion range", according to this invention, the regulator472 is ordered by the controller 435 to decrease the average diameter ofthe droplets.

The change in droplet diameter is preferably conducted in increments,preferably in the range of 10 to 20% of the average droplet diameter atthe particular time.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acid,for example, under certain conditions), said transient conversioncontinues to be monitored with a goal in most cases to stay somewhere inthe vicinity of the middle value of said most desired range (about 40%,for example). As in previous embodiments, continuous monitoring andcontrol are highly preferable, since the conditions in the reactionchamber may vary, causing changes in the transient conversion values.Valves regulating ratios of liquids, and controlled by computerizedcontrollers according to a desirable program are well known in the art.

The device 410 may also optionally comprise an optical monitor 474,preferably of the fiber optic type, connected to an image analyzer 476though line 474', which image analyzer is in turn connected to thecomputerized controller 435 through input line 476'. In operation ofthis arrangement, the image analyzer 476 determines the average dropletdiameter from the image received from the optical monitor 474, and sendsthis information to the controller 435, which then incorporates saidinformation to the rest of the processed data, so that it can be bettercontrol the average droplet diameter, by comparing for example thechange ordered to regulator 472 with the droplet size change as a resultof it.

In a different embodiment of the present invention, better shown in FIG.6, the reaction chamber 512 is provided with an atomizer 526 in thevicinity of its upper end 514, and a sample collector 530 positioned inthe vicinity of its lower end 516. There is also provided a first liquidpump 577, which is adapted to regulate a first flow of the first liquidin line 542, and a flow meter 578 adapted to measure the rate of thefirst flow of the first liquid in line 542. The flow meter 578 isconnected, preferably eclectically, to the computerized controller 535through input line 578'. The sample collector 530 is connected to theconversion monitor or detector 532 through sample line 533 for providingsamples of droplets 548 trapped in the collector just (and coalesced, ofcourse in the collector) before they coalesce onto the second liquidmass 554. The conversion monitor or detector 532 is connected,preferably electrically, to the controller 535 through input line 531for transferring transient conversion information. In turn, thecontroller 535 is connected, preferably electrically, to the firstliquid pump 577 through output line 577' in order to control said firstliquid pump 577. For purposes of clarity, basically only the elements ofthe device 510, which illustrate this embodiment and its operation, areshown.

In operation of this embodiment, the first liquid pump 577 pumps firstliquid in line 542 at a desired first flow rate. Thus, the first liquidcontaining the first reactant, cyclohexane for example, in a firstcontent, enters the reaction chamber 512 through line 542 in a mannerthat it is atomized by the atomizer 526 at a first flow rate, and formsa plurality of droplets 548.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane, enters the chamber 512 through the gas inlet feed line 536,in the vicinity of the lower end 516 of the chamber 512. The gas, inaddition to the second reactant, may also contain rather inert gases,such as nitrogen and/or carbon dioxide, for example. Off gases mixedwith vapors of reactants, solvents, mist, and the like exit the reactionchamber 512 through outlet gas line 525 and are treated as it willexemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 526,they start reacting with the second reactant, which is oxygen forexample. The second liquid 554 is removed, preferably continuously,through the liquid outlet line 524 as in the previous embodiments.

A part of the droplets 548 fall into the sample collector 530, fromwhere, they are directed to the conversion detector or monitor 532, tobe analyzed regarding transient conversion.

The information obtained in the conversion detector or monitor 532 isfed to computerized controller 535 through its input line 531, where itis processed by well known to the art techniques. Also, the flow ratemeasurement from the flow meter 578 is fed to the controller 535 andprocessed in coordination with the information from line 531. Thecontroller 535 in turn controls the first liquid pump 577 through itsoutput line 577', in a manner to increase or decrease the flow rate offirst liquid in a programmed manner.

If the transient conversion is above the pre-coalescing transientconversion range, as earlier defined, the first liquid pump 577 isordered by the controller 535 to increase the first flow rate, byincreasing, for example, the pumping action. Similarly, if the transientconversion is under the pre-coalescing transient conversion range, asearlier defined, the first liquid pump 577 is ordered by the controller535 to decrease the first flow rate, by decreasing, for example, thepumping action.

The change in first flow rate is preferably conducted in increments,preferably in the range of 5 to 10% of the first flow rate at theparticular time.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acid,for example, under certain conditions), said transient conversioncontinues to be monitored with a goal in most cases to stay somewhere inthe vicinity of the middle value of said most desired range (about 40%,for example). As in previous embodiments, continuous monitoring andcontrol are highly preferable, since the conditions in the reactionchamber may vary, causing changes in the transient conversion values.Pumps regulating flow rate of liquids, and controlled by computerizedcontrollers according to a desirable program are well known in the art.

In still a different embodiment of the present invention, better shownin FIG. 7, the reaction chamber 612 is provided with an atomizer 626 inthe vicinity of its upper end 614, and a sample collector 630 positionedin the vicinity of its lower end 616. There is also provided a volatilesmixing valve 679, which is adapted to mix volatiles from line 680 andother liquids from line 681 in order to produce the first liquid in line642. The sample collector 630 is connected to the conversion monitor ordetector 632 through sample line 633 for providing samples of droplets648 trapped in the collector just (and coalesced, of course in thecollector) before they coalesce onto the second liquid mass 654. Theconversion monitor or detector 632 is connected, preferablyelectrically, to the controller 635 through input line 631 fortransferring transient conversion information. In turn, the controller635 is connected, preferably electrically, to the volatiles mixing valve679 through output line 679' in order to control said volatiles mixingvalve 679. For purposes of clarity, basically only the elements of thedevice 610, which illustrate this embodiment and its operation, areshown.

In operation of this embodiment, volatiles from line 680 and otherliquids from line 681 are mixed in proportions regulated by thevolatiles mixing valve 679, in order to produce the first liquid in line642 so that said first liquid has a desired content of volatiles. Thevolatiles are substances, of usually lower boiling point than that ofthe first reactant, which under the conditions of the reaction have atendency to volatilize as the first liquid is atomized in the reactionchamber and lower conversion rates. The volatiles have preferably low orno reactivity under the reaction conditions. In the case of oxidation ofcyclohexane to adipic acid, acetic acid and/or acetone, for example,would represent volatiles.

The liquids from line 681 contain first reactant, along with solvents,catalysts, promoters, initiators, recycled ingredients, and the like.The first liquid containing the first reactant, cyclohexane for example,enters the reaction chamber 612 through line 642 in a manner that it isatomized by the atomizer 626, and forms a plurality of droplets 648.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane for example, enters the chamber 612 through the gas inletfeed line 636, in the vicinity of the lower end 616 of the chamber 612.The gas, in addition to the second reactant, may also contain ratherinert gases, such as nitrogen and/or carbon dioxide, for example. Offgases mixed with vapors of reactants, solvents, mist, and the like exitthe reaction chamber 612 through outlet gas line 625 and are treated asit will exemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 626,they start reacting with the second reactant, which is oxygen forexample. The second liquid 654 is removed, preferably continuously,through the liquid outlet line 624 as in the previous embodiments.

A part of the droplets 648 fall into the sample collector 630, fromwhere, they are directed to the conversion detector or monitor 632, tobe analyzed regarding transient conversion.

The information obtained in the conversion detector or monitor 632 isfed to computerized controller 635 through its input line 631, where itis processed by well known to the art techniques. The controller 635controls the volatiles mixing valve 679 through its output line 679'.

If the transient conversion is above the pre-coalescing transientconversion range, as earlier defined, the volatiles mixing valve 679 isordered by the controller 635 to increase the introduction of volatilesfrom obtained from line 680. Similarly, if the transient conversion isunder the "pre-coalescing transient conversion range", according to thisinvention, the volatiles mixing valve 679 is ordered by the controller635 to decrease or eliminate the introduction of volatiles from line680.

The increase or decrease of volatiles is preferably conducted inincrements, preferably in the range of 2 to 5% based on the total weightof the first liquid at that particular time.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acid,for example, under certain conditions), said transient conversioncontinues to be monitored with a goal in most cases to stay somewhere inthe vicinity of the middle value of said most desired range (about 40%,for example). As in previous embodiments, continuous monitoring andcontrol are highly preferable, since the conditions in the reactionchamber may vary, causing changes in the transient conversion values.Valves regulating ratios of liquids, and controlled by computerizedcontrollers according to a desirable program are well known in the art.

If the liquids in line 681 are arranged to contain no or only smallamounts of catalyst, then catalyst may be added through line 680 at adesired base level. Addition of higher amounts of catalyst will favorincrease of transient conversion, while addition of lower amounts ofcatalyst will favor decrease of transient conversion.

The increase or decrease of catalyst level is preferably conducted inincrements, preferably in the range of 5 to 10% based on the totalweight of the catalyst contained in the first liquid at that particulartime.

In still another embodiment, better shown in FIG. 8, the reactionchamber 712 is provided with an atomizer 726 in the vicinity of itsupper end 714, and a sample collector 730 adapted to be floating as aboat on liquid 754 at the lower end 716 of the reaction chamber 712. Theatomizer 726 is provided with first liquid from line 742, which containsa flow meter 778. There is also provided a retaining tank 753, connectedto the vicinity of the lower end 716 of the reaction chamber 712 throughtwo pumps 751a and 751b. The retaining tank 753 is also connected topump 751c, which is adapted to transfer liquid to a separator (shown as15 in FIG. 1). There is further provided a level controller 755, whichcontrols pump 751c, based on the level of liquid in retaining tank 753,by well known to the art techniques. The level controller activates pump751c through output line 751c' when the liquid exceeds level A, anddeactivates said pump 751c when the liquid goes lower than level B.

The sample collector 730 is connected to the conversion monitor ordetector 732 through sample line 733, which has a flexible coiledportion 733' for providing samples of droplets 748 trapped in thecollector just (and coalesced, of course in the collector) before theycoalesce onto the second liquid mass 754. The sample collector 730 has aboat like configuration provided with a closed float portion 730a, and asample portion 730b, as better shown in FIG. 9. The flexible coiledportion 733' of line 733 allows the boat-like sample collector 730 tomove freely along with the surface 756 of the second liquid mass 754.

The conversion monitor or detector 732 is connected, preferablyelectrically, to the controller 735 through input line 731 fortransferring transient conversion information. Also the flow meter 778is connected, preferably electrically, to the controller 735 throughinput line 778' for transferring flow rate information regarding thefirst liquid entering the reaction chamber 712 through the atomizer 726.In turn, the controller 735 is connected, preferably electrically, topumps 751a' and 751b' through output lines 751a' and 751b',respectively, for controlling said pumps 751a and 751b.

For purposes of clarity, basically only the elements of the device 710,which illustrate this embodiment and its operation, are shown.

In operation of this embodiment, the first liquid containing the firstreactant, cyclohexane for example, enters the reaction chamber 712through line 742 in a manner that it is atomized by the atomizer 726,and forms a plurality of droplets 748.

At the same time that the first liquid is being atomized, a gascontaining the second reactant, preferably oxygen in the case ofcyclohexane for example, enters the chamber 712 through the gas inletfeed line 736, in the vicinity of the lower end 716 of the chamber 712.The gas, in addition to the second reactant, may also contain ratherinert gases, such as nitrogen and/or carbon dioxide, for example. Offgases mixed with vapors of reactants, solvents, mist, and the like exitthe reaction chamber 712 through outlet gas line 725 and are treated asit will exemplified at a later section.

As the droplets fall in a downwardly direction from the atomizer 626,they start reacting with the second reactant, which is oxygen forexample. The second liquid 754 may be removed through the liquid outletline 724 with pump 751a.

A part of the droplets 748 fall into the sample collector 730, fromwhere, they are directed through line 733 and its flexible portion 733'to the conversion detector or monitor 732, to be analyzed regardingtransient conversion.

The information obtained in the conversion detector or monitor 732 isfed to computerized controller 735 through its input line 731, where itis processed by well known to the art techniques. The controller 735controls pumps 751a and 751b, as aforementioned.

If the transient conversion is above the pre-coalescing transientconversion range, as earlier defined, pump 751a is ordered by thecontroller 735 to stop its pumping action, and pump 751b is activated.This causes the surface 756 of the second liquid mass 754 to rise,resulting in smaller atomization distance, as defined earlier. In turn,smaller atomization distance causes the transient conversion todecrease. Similarly, if the transient conversion is under thepre-coalescing transient conversion range, as earlier defined, pump 751ais ordered by the controller 735 to start or continue its pumpingaction, and pump 751b is deactivated. This causes the surface 756 of thesecond liquid mass 754 to drop, resulting in higher atomizationdistance. In turn, higher atomization distance causes the transientconversion to increase.

The level 756 of the second liquid mass 754 may be determined by thecontroller 735 either indirectly by correlating the amounts of incomingfirst liquid (through the atomizer, as measured by the flow meter 778and obtained by the controller 735 through line 778', and through pump751b) and outcoming second liquid 754 through pump 751a, or directly byuse of a level measuring device (not shown for purposes of clarity) inthe reaction chamber. Level measuring devices are well known in the art.

The level of liquids in the retaining tank 753 is controlled by levelcontroller 755. When the level goes under level B, pump 751c isdeactivated by the controller 755. If the liquid level exceeds level A,pump 751c is activated again by controller 755. The retaining pump 753should contain enough liquid at its lowest level B to take care of anygiven variations of liquid level 756 in the reaction chamber 712.

The increase or decrease of atomization distance is preferably conductedin increments, preferably in the range of 2 to 5% of the atomizationdistance at the time the measurement is made.

After the transient conversion is found to be within the most desiredrange (20-60%, for example, in the case of cyclohexane to adipic acid,for example, under certain conditions), said transient conversioncontinues to be monitored with a goal in most cases to stay somewhere inthe vicinity of the middle value of said most desired range (about 40%,for example). As in previous embodiments, continuous monitoring andcontrol are highly preferable, since the conditions in the reactionchamber may vary, causing changes in the transient conversion values.Valves regulating ratios of liquids, and controlled by computerizedcontrollers according to a desirable program are well known in the art.

Going back to FIG. 1, the separator 15, as aforementioned, can be anyassembly of equipment, simple or complicated, which is capable ofseparating the reaction product from the second liquid. Such equipmentis well known to the art, as described for example in a plethora ofpatents regarding separation of adipic acid from the mother liquor(second liquid in this case).

In the case that the reaction product is a solid having limitedsolubility in the second liquid, either at the reaction temperature orany other temperature, as is the case of adipic acid in the case of itsproduction from oxidation of cyclohexane, the separator 15 may comprise,according to this invention, two filters 15a and 15b connected inparallel, as better shown in FIG. 10. The separator 15 may also comprisevalves 15w, 15x, 15y, and 15z, as well as an optional heat removaldevice 15i, which may take the form of a crystallizer.

In operation of this separator, valves 15x and 15y are initially open,while valves 15w and 15z are closed. While valves 15w and 15z areclosed, any solid oxidation product previously accumulated in filter15a, such as adipic acid for example, is separated from said filter 15a,either manually or automatically (back-flush, scraping, and the likewell known to the art, for example/not shown). Second liquid from line24, optionally passing through heat removal device 15i for changing theliquid temperature to a more appropriate temperature for the solidseparation, passes through filter 15b, where the solid oxidation productis removed from the second liquid, which second liquid follows line 11for recirculation to the recirculation tank 19 (FIG. 1) or furtherprocessing in other equipment (not shown). When filter 15a has beensubstantially emptied, and filter 15b has been substantially full orotherwise ready for being emptied, valves 15w and 15z are opened andvalves 15x and 15y are closed, so that filtering of solid oxidationproduct takes place now in filter 15a, while filter 15b is beingemptied. This cycle is repeated in the process. Of course, alternatedevices may be used, such as for example, rotary drum filters and thelike.

In a different embodiment of this invention, better shown in FIG. 11,the apparatus or device 810 of the present invention, also comprises acondenser 857 connected to the gas outlet 823 through line 825, and tocondensate tank 859, which serves as a reservoir of condensate collectedfrom condenser 857. The condensate tank 859, through valve 865 isconnected to line 865', which in turn is connected to the liquiddispensing ring 844, or it is connected to line 865", which in turnleads to line 811 for recycling the condensed liquids to the recyclingtank 819. The valve 865 is adapted to direct the condensed liquidstotally to line 865', or totally to line 865", or partially to line 865'and partially to line 865", or be closed and not permit any transfer ofcondensed liquids.

The device 810 also comprises a heat exchanger 838 connected to therecycling tank 819; an eductor or aspirator 861, connected to the heatexchanger 838; a pump 877 connected to the eductor 861 at the intake andto the atomizer 826 at the other end. The eductor 861 is adapted toproduce vacuum to line 867' through regulating valve 867 (when theregulating valve 867 is in an open position) and through check valve867a, which allows flow from line 867' toward the pump but not viceversa. Line 867' is connected to line 857' between the condenser 857 andthe valve 864. An additional pump (not shown) may be placed between theeductor 861 and the heat exchanger 838, which in coordination with pump877 may control the vacuum produced by the eductor 861 toward line 867'.It may be also utilized to prevent starvation of pump 877 from firstliquid. The heat exchanger 838 may be part of the condenser 857 (notshown as such in FIG. 11), so that heat received from condensibles isused as heat source for the heat exchanger 838.

Lines 841a, 841b, and 841c are used to supply the recirculation tankwith appropriate amounts of raw materials, catalysts, solvents,initiators, promoters and the like.

In operation of this embodiment, first liquid from the recycling tank isheated to the desired temperature in heat exchanger 838. The heatedfirst liquid is pumped through pump 877 to the atomizer 826, where it isbroken into droplets 848, which finally coalesce onto the second liquid854 as already discussed in previous embodiments. At the same time, gascontaining a second reactant, preferably oxygen, enters the reactionchamber 812 in a counterflow direction with regard to the droplets, asalso discussed earlier, and the second reactant reacts with the firstreactant contained in the droplets of the first liquid. Any off-gasesproduced during the reaction, which are usually non-condensible unlesssubjected to extremely low temperatures, along with condensibles leavethe reaction chamber 812 through gas outlet 823. Following line 825,they enter the condenser 857, where the condensibles condense tocondensate, which condensate is accumulated into the condensate tank859.

If it is desired to form a curtain or thick film 845, the condensate isdirected, at least partially, through valve 865 to line 865', from whereit is fed to the liquid dispensing ring 844 and forms said curtain 845,useful to prevent sticking of any reaction or other solid products tothe walls of the reactor 812. This condensate has the advantage over therecycled liquid coming through line 11' of FIG. 1, for example, that inmost cases it is substantially catalyst free. This is because in thepractice of this invention, non volatile catalysts, such as metal saltsfor example, are utilized in most occasions.

If no condensate is needed to supply the liquid dispensing ring, the 865is caused to direct the condensate to line 865", which feeds it to line811, so that the condensate is finally transferred to the recirculationtank 819. In general, as aforementioned, the valve 865 is adapted todirect the condensed liquids totally to line 865', or totally to line865", or partially to line 865' and partially to line 865", or be closedand not permit any transfer of condensed liquids.

The non-condensible gases follow line 857', and exit the system throughvalve 864, if so desired. Valve 864, as also shown in other embodiments,is preferably controllable to open and close to any degree demanded bythe operation. If it is desired to remove all non-condensible gases fromthe system, valve 864 is opened to a desired degree for the pressureinside the system to be maintained to desired levels, and valve 867 iscompletely closed. If it is desired to only partially removenon-condensibles, both valves 864 and 867 are opened to the desireddegree, so that vacuum formed by the eductor or aspirator 861,recirculates the part of non-condensibles caused by the vacuum to enterthe reaction chamber 812. Complete recirculation of non-condensibleswithout any non-condensibles leaving the system is only possible if nonew flow of gas containing second reactant takes place after a certainpoint, so that the pressure inside the reaction chamber 812 will notfinally exceed predetermined limits. Check valve 867a does not hinderthe flow of non-condensibles, but it prevents entry of first liquid toline 867' in case of accidental flooding of the aspirator 861.

In still a different embodiment of this invention, better shown in FIG.12, the apparatus or device 910 of the present invention, also comprisesa condenser 957 connected to the gas outlet 923 through line 925, and tocondensate tank 959, which serves as a reservoir of condensate collectedfrom condenser 957. The condensate tank 959, is connected to the liquiddispensing ring 944. The condenser 957 is also connected to a valve 964through line 957', which valve is adapted to release non-condensibles,if in an open position.

The device 910 also comprises a heat exchanger 938 connected to therecycling tank 919 and to the atomizer 926 at the other end. It alsocomprises a gas pump 961 connected to line 957' through line 967'adapted to transfer non-condensibles from line 957' to the gas inletfeed line 936. A replenish gas line 936' is also connected to line 936for providing fresh gas containing second reactant, preferably oxygen.

The heat exchanger 938 may be part of the condenser 957 (not shown assuch in FIG. 11), so that heat received from condensibles is used asheat source for the heat exchanger 938.

Lines 941a, 941b, and 941c are used to supply the recirculation tankwith appropriate amounts of raw materials, catalysts, solvents,initiators, promoters and the like.

In operation of this embodiment, first liquid from the recycling tank isheated to the desired temperature in heat exchanger 938, and enters theatomizer 926, where it is broken into droplets 948, which finallycoalesce onto the second liquid 954 as already discussed in previousembodiments. At the same time, gas containing second reactant,preferably oxygen, enters the reaction chamber 912 through line 936 in acounterflow direction with regard to the droplets, as also discussedearlier, and the second reactant reacts with the first reactantcontained in the droplets of the first liquid. Any off-gases producedduring the reaction, which are usually non-condensible unless subjectedto extremely low temperatures, along with condensibles leave thereaction chamber 912 through gas outlet 923. Following line 925, theyenter the condenser 957, where the condensibles condense to acondensate, which condensate is accumulated into the condensate tank959.

The condensate is directed, at least partially as discussed in otherembodiments, to the liquid dispensing ring 944 and forms curtain 945,useful to prevent sticking of any reaction or other solid products tothe walls of the reactor 912. This condensate has the advantage over therecycled liquid coming through line 11' of FIG. 1, for example, that inmost cases it is substantially catalyst free. This is because in thepractice of this invention, non volatile catalysts, such as metal saltsfor example, are utilized in most occasions.

If no condensate is needed to supply the liquid dispensing ring 944, thecondensate may be directed elsewhere through line 959'.

The non-condensible gases follow line 957', and exit the system throughvalve 964, if so desired. Valve 964, as also shown in other embodiments,is preferably controllable to open and close to any degree demanded bythe operation. If it is desired to remove all non-condensible gases fromthe system, valve 964 is opened to a desired degree for the pressureinside the system to be maintained to desired levels, and pump 961 isdeactivated. If it is desired to have only partial removal ofnon-condensibles, valve 964 is opened to the desired degree, and pump961 is also activated to the desired degree so that this combinationcauses recirculation of part of non-condensibles to the reaction chamber912. Complete recirculation of non-condensibles without substantiallyany non-condensibles leaving the system may be preferably conducted bynot allowing new flow of inert gas diluents to take place after acertain point, so that the pressure inside the reaction chamber 912 doesnot finally exceed predetermined limits.

The second liquid 954 is directed to the separator 915, through line924, where the reaction product is separated and the remaining liquidsare either sent to another separator (not shown) for further separationof constituents, or they are directed to the recycling tank 919 forrecycling, or a combination thereof.

In another embodiment of this invention, better shown in FIG. 13, thereaction chamber 1012 has a gas outlet 1023, which coincides with theliquid outlet 1022, preferably in the vicinity of the lower end 1016 ofthe reaction chamber 1012. Both the gas distributor 1073 fed by gasinlet line 1036, and the atomizer 1026 fed by line 1042, are preferablydisposed at the upper end 1014 of the reaction chamber 1012. The gasdistributor 1073 and the atomizer 1026 may be combined into one unit,and the gas may be used to help or totally be responsible for theatomization process.

The liquid/gas output 1022/1023 has preferably a conical shape ofreduced diameter as compared to the diameter of the reaction chamber1012, as illustrated in FIG. 13. The liquid dispensing ring 1044 ispreferably positioned either at the bottom of the reaction chamber asshown in FIG. 13, or at the top 1023' of the liquid/gas output1022/1023. Preferably, the liquid dispensing ring 1044 is adapted todeliver the liquids in a swirling manner. A cooler (not shown) may beplaced in line 1011' in order to cool the liquids to a desiredtemperature adequate to condense condensibles exiting from the reactionchamber 1012 through the liquid/gas output 1022/1023.

There is also provided a liquid/gas separator 1075 for receiving thecondensed condensibles and the non-condensibles from the reactionchamber 1012 through line 1025 and separating the second liquid 1054from the non-condensibles. The liquid/gas separator 1075 is in turnconnected to separator 1015, which is adapted to separate the reactionproduct from the reactants and other materials introduced into thesystem in the process.

In operation of this embodiment, first liquid is introduced to theatomizer 1026 through line 1042, where it is broken into droplets 1048,which finally coalesces in the vicinity of the lower end 1016,preferably on the curtain or thick film 1045 and within the liquid/gasoutput 1022/1023. At the same time, gas containing a second reactant,preferably oxygen, enters the reaction chamber 1012 in the samedirection with regard to movement of the droplets, and the secondreactant reacts with the first reactant contained in the droplets of thefirst liquid as both droplets and gas travel in a direction from theupper end 1014 to the lower end 1016 of the reaction chamber 1012.Condensibles condense on the swirling cold liquids entering the systemthrough line 1011'. The liquids coming in the reaction chamber throughline 1011' may be derived from within the system or from outside thesystem. Any off-gases produced during the reaction, which are usuallynon-condensible unless subjected to low temperatures, along withcondensibles leave the reaction chamber 1012 through the liquid/gasoutput 1022/1023. Following line 1025, they enter the liquid/gasseparator 1075, where the second liquid 1054 is separated from thenon-condensibles, which are removed through line 1057' and valve 1064,which valve may operate as already discussed in previous embodiments.

The second liquid 1054 is directed to the separator 1015, where it istreated as already discussed in previous embodiments.

As mentioned earlier, condensation of condensibles may be inside thepressurized device, such as for example device 810 and 910 of FIGS. 11and 12, respectively, in the respective condensers 857 and 957, beforethe respective valves 864 and 964, which are used to purge the noncondensibles, such as miscellaneous off-gases, which may include one ormore of oxygen, nitrogen, carbon monoxide, carbon dioxide, and the like,for example. This particular type of condensation, albeit outside thereaction chamber, is by definition internal condensation, according tothis invention, and it takes place at a pressure which is substantiallythe same as the reaction pressure.

According to this invention, internal condensation inside the reactormay also take place, and in many occasions it is preferable to theoutside internal condensation. Internal condensation (before substantialpressure drop) is highly preferable to external condensation (aftersubstantial or total pressure drop). Internal inside condensation isespecially suitable in the case of employing close to stoichiometricamounts of second reactant for the reaction process.

One embodiment of the instant invention utilizing internal insidecondensation is better shown in FIG. 14, wherein only a limited numberof elements is shown, for purposes of clarity. There is provided acooling mantle 1183 surrounding the reaction chamber 1112 in all or partof its height. Otherwise, the reaction chamber 1112 comprises the sameelements as in the previous embodiments.

The operation of this embodiment is similar to the operation of theprevious embodiments with the exception that a cooler enters the mantle1183 through line 1182 and exits through line 1182'. The temperature ofthe cooler is such as to cool down the wall 1120 adequately for vaporsof condensibles inside the reaction chamber to condense and form a thickfilm or curtain 1145. Since the catalyst (metal salt for example, suchas cobalt acetate, for example) in most cases is not volatile, it doesnot transfer to this curtain. Further, the temperature of the thick filmis lower than that of the temperature of the droplets. Thus, nosubstantial reaction takes place within the curtain, and in addition toother advantages, the thick film or curtain 1145 prevents solid buildupon the walls of the condenser.

Another embodiment of the instant invention utilizing internal insidecondensation is better shown in FIG. 15, wherein only a limited numberof elements is shown, for purposes of clarity. There is provided acooling coil 1283 inside the reaction chamber 1212, having an entrycoolant line 1282 and a coolant exit line 1282'. The coil may beextending through the whole height of the reactor or just through partof it. The coil 1283 may be positioned vertical as shown in FIG. 15, orhorizontal, or it may have any other suitable for the circumstancesdirection. Otherwise, the reaction chamber 1212 comprises the sameelements as in the previous embodiments.

The operation of this embodiment is similar to the operation of theprevious embodiments with the exception that a cooler enters the coil1283 through line 1282 and exits through line 1282'. The temperature ofthe cooler is such as to cool down the coil 1283 adequately for vaporsof condensibles inside the reaction chamber to condense on said coil1283. Since the catalyst (metal salt for example, such as cobaltacetate, for example) in most cases is not volatile, it does nottransfer to the condensate on the coil. Further, the temperature of thecondensate on the coil 1283 is lower than that of the temperature of thedroplets. Thus, reactants and catalysts contained in droplets coalescingon the coil are considerably diluted, and no substantial reaction takesplace within a thick film (not shown) formed on the coil from condensateand coalesced droplets. The thick film also prevents solid buildup onthe coil.

Still another embodiment of the instant invention utilizing internalinside condensation is better shown in FIG. 16, wherein only a limitednumber of elements is shown, for purposes of clarity. There is provideda cooling liquid sprayer 1385, preferably at the upper end 1314 of thereaction chamber 1312, and even more preferably disposed on top of theatomizer 1326, having an entry cooling liquid line 1384. Otherwise, thereaction chamber 1312 comprises the same elements as in the previousembodiments.

The operation of this embodiment is similar to the operation of theprevious embodiments with the exception that a cooling liquid enters thecooling liquid sprayer 1385 through line 1384. It is then atomized bysprayer 1385. The cooling liquid comprises preferably either the samesolvent contained in the first liquid or first reactant contained in thefirst liquid. For example, in the case of preparation of adipic acidfrom cyclohexane, the cooling liquid preferably comprises acetic acid(solvent), or cyclohexane (first reactant), or a mixture thereof.Preferably, no catalyst is contained in the cooling liquid. Thetemperature at which the cooling liquid is atomized is such thatcondensibles condense on the droplets of the atomized cooling liquid,thus providing internal inside condensation. As aforementioned, thedroplets of the first liquid do not mix with the cooling liquiddroplets, for all practical purposes, while both are being suspended inthe gas, so that reaction proceeds unhindered within the droplets of thefirst liquid. Finally, both types of droplets coalesce together at thelower end 1316 of the reaction chamber 1312 to form the second liquid1354, which is removed through line 1324 for further treatment, asdescribed in previous embodiments. In determination of the transientconversion, the flow rate of the cooling liquid and the flow rate of thefirst liquid have to be taken into account by well known to the arttechniques in the controller (for example shown as 35 in FIG. 1).

A different embodiment of the instant invention utilizing internalinside condensation is better shown in FIG. 17, wherein only a limitednumber of elements is shown, for purposes of clarity. There is provideda cooling liquid sprayer 1485, preferably at the upper end 1414 of thereaction chamber 1412 having an entry cooling liquid line 1484. Thesprayer 1485 has preferably a plurality of spray nozzles 1486 around itsperimeter. The spray nozzles 1486 are directed toward the wall 1420 ofthe reaction chamber 1412. Otherwise, the reaction chamber 1412comprises the same elements as in the previous embodiments.

The operation of this embodiment is similar to the operation of theprevious embodiments with the exception that a cooling liquid enters thecooling liquid sprayer 1485 through line 1484. It is then atomized bysprayer 1485 through nozzles 1486, and falls on the walls 1420 of thereaction chamber 1412, where it forms a thick film or curtain 1445. Thecooling liquid comprises preferably either the same solvent contained inthe first liquid or first reactant contained in the first liquid. Forexample, in the case of preparation of adipic acid from cyclohexane, thecooling liquid preferably comprises acetic acid (solvent), orcyclohexane (first reactant), or a mixture thereof. Preferably, nocatalyst is contained in the cooling liquid. The temperature at whichthe cooling liquid is atomized is such that condensibles condense on thedroplets of the atomized cooling liquid, and also on the curtain 1445,thus providing internal inside condensation. Since the catalyst (metalsalt for example, such as cobalt acetate, for example) in most cases isnot volatile, it does not transfer to the curtain 1445. Further, thetemperature of the thick film is lower than that of the temperature ofthe first liquid droplets. Thus, no substantial reaction takes placewithin the curtain 1445, and in addition to other advantages, the thickfilm or curtain 1445 prevents solid buildup on the walls of thecondenser. Liquids and droplets ar finally mixed together at the lowerend 1416 of the reaction chamber 1412, as the second liquid 1454, whichis removed through line 1424 for further treatment, as described inprevious embodiments.

Many catalysts used for reactions, such as oxidations for example, aretransition metals having more than one valence states. Their majorcatalytic action is exhibited when they are at a higher valance statethan their lowest valance state at which they exist as ions. One goodexample is cobalt in the case of oxidation of cyclohexane to adipicacid. An initiation period before the oxidation starts has often beenattributed by researches to the addition of cobalt ions at a valancestate of II. The cobalt catalyst is added at valance state II becausecobaltous acetate, for example, is more readily available and it is lessexpensive than cobaltic acetate. Thus, it takes a period of time for thecobaltous ion to be oxidized to cobaltic ion and start acting as acatalyst according to methods in the art so far, unless cobalt II isused, or the cobalt II is preoxidized. Even then, it takes time tooxidize cobalt II to cobalt III ions, due to the small interfaceprovided by bubbling the gas through the solution.

In the case of the instant invention, this period of oxidation becomesconsiderably smaller because of the high surface area provided.

In addition, the cobaltous ion can be pre-oxidized using substantiallythe methods and devices of the instant invention. In this respect, thecobaltous ions, in the form of cobaltous acetate tetrahydrate forexample are dissolved in water, acetic acid, or a mixture thereof, forexample, to form a solution. In a reaction chamber 1512, similar theaforedescribed reaction chambers, better shown in FIG. 18, the solutionis broken to droplets by an atomizer 1526 in a stream of a gascontaining a second reactant, preferably oxygen, for example. The gasenters the reaction chamber 1512 through line 1591 and leaves throughexhaust line 1525. It is recirculated through line 1587 from thesolution 1554 to the atomizer 1526 by means of a pump 1588. Cobalt IIions in the droplets are oxidized fast to cobalt III ions, due not onlyto the huge surface area, but also to the fact that the second reactanthas only very small distances to travel within each droplet, in order toaffect the total liquid. A sampling monitor (not shown) follows theprogress of the oxidation. The sampling monitor may use any of theanalytical techniques, well known to the art, for determining theprogress of oxidation. When a substantial amount of Co (II) has beenoxidized to Co (III), the solution 1554 is transferred to a retainingtank 1592 through line 1589, from which, it is added to any appropriatestage of the process. For example, in the case of the embodiment shownin FIG. 1, it may be added in the recirculation tank 19, or in line 41,or in line 42. For other catalyst systems comprising other than cobaltmetal ions, the same process may be used, so as to cause at leastpartial oxidation of the lower valance state ions to ions of highervalance state in the solution of said metal catalyst.

As aforementioned, reactions, such as oxidations for example, accordingto this invention, are non-destructive oxidations, wherein the oxidationproduct is different than carbon monoxide, carbon dioxide, and a mixturethereof. Of course, small amounts of these compounds may be formed alongwith the oxidation product, which may be one product or a mixture ofproducts.

Examples include, but of course, are not limited to

preparation of C₅ -C₈ aliphatic dibasic acids from the correspondingsaturated cycloaliphatic hydrocarbons, such as for example preparationof adipic acid from cyclohexane;

preparation of C₅ -C₈ aliphatic dibasic acids from the correspondingketones, alcohols, and hydroperoxides of saturated cycloaliphatichydrocarbons, such as for example preparation of adipic acid fromcyclohexanone, cyclohexanol, and cyclohexylhydroperoxide;

preparation of C₅ -C₈ cyclic ketones, alcohols, and hydroperoxides fromthe corresponding saturated cycloaliphatic hydrocarbons, such as forexample preparation of cyclohexanone, cyclohexanol, andcyclohexylhydroperoxide from cyclohexane; and

preparation of aromatic multi-acids from the corresponding multi-alkylaromatic compounds, such as for example preparation of phthalic acid,isophthalic acid, and terephthalic acid from o-xylene, m-xylene andp-xylene, respectively.

Regarding adipic acid, the preparation of which is especially suited tothe methods and devices or apparatuses of this invention, generalinformation may be found in a plethora of U.S. Patents, among otherreferences. These, include, but are not limited to:

U.S. Pat Nos. 2,223,493; 2,589,648; 2,285,914; 3,231,608; 3,234,271;3,361,806; 3,390,174; 3,530,185; 3,649,685; 3,657,334; 3,957,876;3,987,100; 4,032,569; 4,105,856; 4,158,739 (glutaric acid); 4,263,453;4,331,608; 4,606,863; 4,902,827; 5,221,800; and 5,321,157.

Examples demonstrating the operation of the instant invention have beengiven for illustration purposes only, and should not be construed aslimiting the scope of this invention in any way. In addition it shouldbe stressed that the preferred embodiments discussed in detailhereinabove, as well as any other embodiments encompassed within thelimits of the instant invention, may be practiced individually, or inany combination thereof, according to common sense and/or expertopinion. Individual sections of the embodiments may also be practicedindividually or in combination with other individual sections ofembodiments or embodiments in their totality, according to the presentinvention. These combinations also lie within the realm of the presentinvention. Furthermore, any attempted explanations in the discussion areonly speculative and are not intended to narrow the limits of thisinvention.

In the different figures of the drawing, numerals differing by 100represent elements which are either substantially the same or performthe same function. Therefore, in the case that one element has beendefined once in a certain embodiment, its re-definition in otherembodiments illustrated in the figures by the same numerals or numeralsdiffering by 100 is not necessary, and it has been often omitted in theabove description for purposes of brevity. Thus, for example, referencesign 127 is the same as 27, which is a plurality of nozzles; 336 is thesame as 36, which is a gas inlet feed line; 815 and 1015 are separators,similar to separator 15; 824, 924, 1024, 1124, and 1224 are liquidoutlet lines similar to liquid outlet line 24; 836 and 1136 are gasinlet feed lines similar to gas inlet feed line 36; 942, 1142, 1242,1342, and 1442 are lines similar to line 42 providing the respectivenozzles with mixture; 911 and 1011 are lines similar to line 11 forreturning reactants, solvents, catalysts, and the like, to arecirculation tank from a separator; 1010 is a device similar to thedevice 10 depicted in FIG. 1 and described earlier in detail; 1025,1125, 1225, and 1325 are outlet gas lines similar to the outlet gas line25 depicted in FIG. 1; 1126 and 1426 are atomizers, similar to atomizer26, depicted in FIG. 1; 1316 is the lower end of the reaction chamber,similar to the lower end 16 of the reaction chamber, as depicted in FIG.1; 1354 is the second liquid, similar to the second liquid 54 depictedin FIG. 1.

The words "inlet line" and "outlet line" have been used to signify linesadapted to transfer materials for the operation of the process, such asvolatiles, reaction products, off-gases, and the like, for example. Thewords "input line" and "output line" have been used to signify linesadapted to transmit signals, which are mostly electrical, but they couldalso be hydraulic, pneumatic, optical, acoustic, and the like, forexample.

A diagonal arrow through an element denotes that the element iscontrolled though a line, preferably electrical, connected to the arrow.

Internal condensation according to this invention is condensation ofcondensibles, which takes place within the pressurized system and beforepressure drop to about atmospheric pressure.

Condensibles are substances having a boiling point higher than 15° C.,while non condensibles are substances that have a boiling point of 15°C. and lower. It should be understood that when referring tocondensibles, it is meant "mostly condensibles" and when referring tonon-condensibles it is meant "mostly non-condensibles", since smallamounts of one kind will be mixed with the other kind at substantiallyall times.

More specifically the transient conversion is defined as the ratio

    (O.sup.2 --O.sup.1)x100/R.sup.1 xn

where,

O¹ is the percent moles of reaction product in the first liquid;

O² is the percent moles of reaction product as provided to theconversion monitor by the sample collector;

R¹ is the percent moles of first reactant in the first liquid; and

n is the number of moles reaction product produced when one mole offirst reactant is completely converted to said reaction product.

In other words, transient conversion is the conversion taking place inthe time interval between the formation of the droplets and theircoalescence into a mass of liquid.

In cases where dilution or concentration of the droplets occurs as theytravel from the atomizer to the sample collector, such dilution has tobe taken into acount in the calculation of transient conversion in theappropriately programmed controller by monitoring the sources ofdilution or concentration using well known to the art techniques.

Response time between changing one variable or parameter and the resultit brings about should also be taken into account, and the controllercalibrated or programmed accordingly, by well known to the arttechniques.

What is claimed is:
 1. A device for preparing a reaction product from afirst liquid containing a first reactant and a gas containing a secondreactant comprising:a reaction chamber having an upper end, a lower end,a wall, and a reaction zone, in which zone the first liquid is broughtin contact with the gas for reacting at a reaction pressure; an atomizerdisposed within the reaction chamber adapted to break the first liquidinto a plurality of droplets within the gas at an atomizationtemperature in a manner that the droplets coalesce on a mass of a secondliquid containing reaction product, the mass of the second liquid havinga second liquid surface, the atomizer being away from said second liquidsurface at an atomization distance; a conversion detector for monitoringtransient conversion of the first reactant and the second reactant toreaction product in the droplets before the droplets coalesce onto themass of the second liquid; a control means connected to the conversiondetector for pointing said transient conversion in the droplets toward apredetermined conversion range; and a separator for separating thereaction product from the second liquid.
 2. A device as defined in claim1, wherein the droplets have an average droplet diameter and areproduced at a desired first flow rate, the gas flows at a second flowrate, the droplets contain volatile ingredients volatilizing at avolatilization rate, the first liquid contains first reactant at a firstcontent, the gas contains second reactant at a second content, andwherein the control means comprise means for changing a variableselected from a group consisting ofthe atomization temperature, thereaction pressure, the atomization distance, the average dropletdiameter, the first flow rate, the second flow rate, the volatilizationrate, the first content, the second content, anda combination thereof.3. A device as defined in claim 2, wherein the conversion detectorcomprises a chromatography apparatus.
 4. A device as defined in claim 2,wherein the conversion detector comprises a High Performance LiquidChromatography apparatus.
 5. A device as defined in claim 1, wherein theatomizer is disposed toward the upper end, and directed toward the lowerend at the atomization distance.
 6. A device as defined in claim 5,wherein the atomizer is airless.
 7. A device as defined in claim 1,further comprising a recirculation branch for recirculating at leastpart of the second liquid.
 8. A device as defined in claim 7, furthercomprising a recirculation tank for providing a third liquid containingfirst reactant to be added to the first liquid to replenish firstreactant consumed during the reaction.
 9. A device as defined in claim1, wherein the reaction product is a solid, and the separator comprisesa filtration apparatus for separating at least part of said reactionproduct from the second liquid.
 10. A device as defined in claim 1,further comprising means for adding an antistatic compound to acomponent selected from a group consisting of the first liquid, the gas,and a combination thereof, in order to prevent development ofelectrostatic charges and sparking.
 11. A device as defined in claim 10,wherein the antistatic compound comprises water.
 12. A device as definedin claim 1, further comprising an internal condenser for condensingcondensibles at substantially reaction pressure.
 13. A device as definedin claim 1, further comprising means for providing a film of liquid orcurtain on the wall.
 14. A device as defined in claim 1, furthercomprising a second reaction chamber and a second atomizer inside saidsecond reaction chamber adapted to atomize a solution comprising metalions of a lower oxidation state in a manner to form a plurality ofdroplets in the second reaction chamber, the second reaction chambercontaining a gas comprising an oxidant adapted to cause at least partialoxidation of the metal ions to a higher valance state, the devicefurther comprising means for feeding the solution containing theoxidized metal ions to a desired section of the device.